<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>0008 - Disclosure - Summary of Significant Accounting Policies</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><CurrencyCode /><FootnoteIndexer /><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios><MCU><KeyName /><CurrencySymbol /><contextRef><ContextID>From2013-01-01to2013-06-30</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001341768</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2013-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-06-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="6 Months Ended" /><Label Key="Calendar" Id="1" Label="Jun. 30, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>1</Level><ElementName>DEEL_NotesToFinancialStatementsAbstract</ElementName><ElementPrefix>DEEL_</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Notes to Financial Statements</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_SignificantAccountingPoliciesTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="From2013-01-01to2013-06-30" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Accounting Principles&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The consolidated balance sheets and related
consolidated statements of operations and cash flows contained in this report include the accounts of the Company and its subsidiaries.
All significant intercompany balances and transactions have been eliminated in consolidation. In the opinion of management, all
entries necessary for a fair presentation of such consolidated financial statements have been included. These entries consisted
only of normal recurring items.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The consolidated financial statements and accompanying
notes are prepared in accordance with generally accepted accounting principles in the United States of America (&amp;#147;GAAP&amp;#148;).
The preparation of financial statements in conformity with United States generally accepted accounting principles requires management
to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets
and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the
reporting period. Actual results may differ from those estimates.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"&gt;&lt;b&gt;&lt;i&gt;&amp;#160;&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Discontinued operations&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The Company&amp;#146;s former operations were
discontinued in 2008 and were accounted for as discontinued operations. On October 21, 2011, the discontinued operations of QMotions,
Inc. and Aptus Games Inc. were sold in a share purchase agreement to an individual. The Company retains ownership of the discontinued
subsidiary Diagnostic Nano Applications Corp.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Cash and cash equivalents&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;Cash and cash equivalents consist primarily
of cash on deposit.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Revenue recognition&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The Company recognizes revenue in accordance
with the provision of the Securities and Exchange Commission Staff Accounting Bulletin (&amp;#147;SAB&amp;#148;) No. 104 (ASC 605-10)
which establishes guidance in applying generally accepted accounting principles to revenue recognition in financial statements.
Four basic criteria must be met before we recognize revenue: (1) persuasive evidence of an arrangement exists; (2) delivery has
occurred or services rendered; (3) the price to the buyer is fixed and determinable; and (4) collectability is reasonably assured.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Research and development&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;All costs of research and development activities
are expensed as incurred.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Income taxes&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The Company records deferred tax assets and
liabilities based on the net tax effects of tax credits, operating loss carryforwards and temporary differences between the carrying
amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The Company assesses
the likelihood that its deferred tax assets will be recovered from future taxable income and the Company establishes a valuation
allowance to reduce deferred tax assets to an amount which it believes to be more likely than not realizable. The valuation allowance
is based on the Company`s estimates of taxable income by jurisdiction in which it operates and the period over which its deferred
tax assets will be recoverable.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Going concern&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The accompanying consolidated financial statements
have been prepared assuming that the company will continue to operate as a going concern. Through June 30, 2013, the Company has
not generated significant operating or net profits. As of June 30, 2013, the accumulated deficit is $9,324,214 and the working
capital deficiency is $2,072,653.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"&gt;&lt;b&gt;&lt;i&gt;&amp;#160;&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Property, plant and equipment&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;Property, plant and equipment are stated at
original cost less accumulated depreciation and amortization.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;Depreciation is provided to write off the cost
of property, plant and equipment using the straight-line method at rates based on their estimated useful lives from the date on
which they become fully operational and after taking into account their estimated residual values.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"&gt;&lt;b&gt;&lt;i&gt;&amp;#160;&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Accounting for the impairment of long-lived
assets&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The long-lived assets held and used by the
Company are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of assets may
not be recoverable. It is reasonably possible that these assets could become impaired as a result of technology or other industry
changes. Determination of recoverability of assets to be held and used is by comparing the carrying amount of an asset to future
net undiscounted cash flows to be generated by the assets. If such assets are considered to be impaired, the impairment to be recognized
is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets. Assets to be disposed
of are reported at the lower of the carrying amount or fair value less costs to sell.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Operating leases&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;Leases where substantially all the rewards
and risks of ownership of assets remain with the leasing company are accounted for as operating leases.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;br /&gt;
&lt;b&gt;&lt;i&gt;Fair Value of Financial Instruments&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;The Company&amp;#146;s financial instruments consist
of prepaids and other assets, accounts payable, accrued interest, and notes payable. The carrying amounts of these financial instruments
approximates fair value due either to length of maturity or interest rates that approximate prevailing market rates unless otherwise
disclosed in these financial statements.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"&gt;&lt;b&gt;&lt;i&gt;&amp;#160;&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Related parties&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;Parties are considered to be related if one
party has the ability, directly or indirectly, to control the other party or exercise significant influence over the other party
in making financial and operating decisions. Parties are also considered to be related if they are subject to common control or
common significant influence.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Basic and Diluted Net Loss per Share&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;Basic net loss per common share is computed
by dividing net loss applicable to common shareholders by the weighted-average number of common shares outstanding during the period.
Diluted net loss per common share is determined using the weighted-average number of common shares outstanding during the period,
adjusted for the dilutive effect of common stock equivalents, consisting of shares that might be issued upon exercise of common
stock options. In periods where losses are reported, the weighted-average number of common shares outstanding excludes common stock
equivalents, because their inclusion would be anti-dilutive.&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&amp;#160;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;&lt;b&gt;&lt;i&gt;Recently issued accounting standards&lt;/i&gt;&lt;/b&gt;&lt;/p&gt;

&lt;p style="font: 10pt Times New Roman, Times, Serif; margin: 0; text-align: justify"&gt;There are no accounting standards or interpretations
issued or recently adopted that are expected to have a material impact on the Company&amp;#146;s consolidated financial position,
operations or cash flows.&lt;/p&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for all significant accounting policies of the reporting entity.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

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 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



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