<?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>008 - Disclosure - Basis of Presentation</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

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</LabelSeparator><Level>1</Level><ElementName>us-gaap_AccountingPoliciesAbstract</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="" 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>Basis of Presentation and Summary of Significant Accounting Policies [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock</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><PreferredLabelRole>verboseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="Context_6ME__30-Jun-2013" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt; font-weight: bold;"&gt;1. Basis of Presentation&lt;/font&gt;&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;"&gt;The accompanying unaudited condensed consolidated financial statements include the accounts of Snap Interactive, Inc. and its wholly owned subsidiaries, eTwine, Inc. and Snap Mobile Limited.&amp;#160;&amp;#160;The condensed consolidated financial statements included in this report have been prepared in accordance with generally accepted accounting principles in the United States of America (&amp;#8220;GAAP&amp;#8221;) and the rules and regulations of the Securities and Exchange Commission (the &amp;#8220;SEC&amp;#8221;) for interim financial information.&amp;#160;&amp;#160; We have not included certain information normally included in annual financial statements pursuant to those rules and regulations, although we believe that the disclosure included herein is adequate to make the information presented not misleading.&lt;/font&gt;&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;
&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;"&gt;The financial statements contained herein should be read in conjunction with the Company&amp;#8217;s audited&amp;#160;consolidated financial statements and the related notes to the audited consolidated financial statements included in the Company&amp;#8217;s Annual Report on Form 10-K for the year ended December 31, 2012, filed with the SEC on March 14, 2013.&lt;/font&gt;&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;"&gt;In the opinion of management, the accompanying unaudited condensed consolidated financial information contains all normal and recurring adjustments necessary to fairly present the consolidated financial condition, results of operations, and changes in cash flows of the Company for the interim periods presented.&amp;#160;&amp;#160;The Company&amp;#8217;s historical results are not necessarily indicative of future operating results and the results for the six months ended June 30, 2013 are not necessarily indicative of results for the year ending December 31, 2013, or for any other period.&lt;/font&gt;&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&amp;#160;&lt;/div&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;
&lt;div align="left" style="text-indent: 0pt; display: block; margin-left: 0pt; margin-right: 0pt;"&gt;&lt;font style="display: inline; font-family: times new roman; font-size: 10pt;"&gt;Certain amounts from prior periods have been reclassified to conform to the current period presentation.&lt;/font&gt;&lt;/div&gt;
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