<?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>115 - Disclosure - Goodwill</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>eol_PE677256--1310-K0007_STD_365_20130430_0</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001330421</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2012-05-01T00:00:00</PeriodStartDate><PeriodEndDate>2013-04-30T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS /><CurrencyCode /><OriginalCurrencyCode /></MCU><CurrencySymbol /><Labels><Label Key="CalendarSupplement" Id="0" Label="12 Months Ended" /><Label Key="Calendar" Id="1" Label="Apr. 30, 2013" /></Labels></Column></Columns><Rows><Row FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>4</Level><ElementName>us-gaap_GoodwillDisclosureTextBlock</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>terseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="eol_PE677256--1310-K0007_STD_365_20130430_0" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div&gt;
&lt;p style="margin-top:18px;margin-bottom:0px"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&lt;b&gt;6.
Goodwill&lt;/b&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top:6px;margin-bottom:0px; text-indent:4%"&gt;
&lt;font style="font-family:Times New Roman" size="2"&gt;At
April&amp;#xA0;30, 2013, the Company had goodwill in the amount of
$141.8 million. The Company assesses goodwill for impairment
annually in the fourth fiscal quarter or more frequently if other
indicators of potential impairment arise. There were no indicators
of impairment during the year ended April 30, 2013 and no
impairment was identified in the Company&amp;#x2019;s annual
assessment.&lt;/font&gt;&lt;/p&gt;
&lt;p style="margin-top:12px;margin-bottom:0px; text-indent:4%"&gt;
&lt;font style="font-family:Times New Roman" size="2"&gt;The following
table reflects the changes in goodwill for the year ended
April&amp;#xA0;30, 2013 (in thousands):&lt;/font&gt;&lt;/p&gt;
&lt;p style="font-size:12px;margin-top:0px;margin-bottom:0px"&gt;
&amp;#xA0;&lt;/p&gt;
&lt;table cellspacing="0" cellpadding="0" width="68%" border="0" style="BORDER-COLLAPSE:COLLAPSE" align="center"&gt;
&lt;tr&gt;
&lt;td width="83%"&gt;&lt;/td&gt;
&lt;td valign="bottom" width="7%"&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr bgcolor="#CCEEFF"&gt;
&lt;td valign="top"&gt;
&lt;p style="margin-left:1.00em; text-indent:-1.00em"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;Balance, as of
April&amp;#xA0;30, 2012&lt;/font&gt;&lt;/p&gt;
&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font size="1"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;$&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom" align="right"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&amp;#x2014;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;td nowrap="nowrap" valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td valign="top"&gt;
&lt;p style="margin-left:1.00em; text-indent:-1.00em"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;Increase in goodwill related
to PowerReviews acquisition&lt;/font&gt;&lt;/p&gt;
&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font size="1"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom" align="right"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;113,152&lt;/font&gt;&lt;/td&gt;
&lt;td nowrap="nowrap" valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr bgcolor="#CCEEFF"&gt;
&lt;td valign="top"&gt;
&lt;p style="margin-left:1.00em; text-indent:-1.00em"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;Increase in goodwill related
to Longboard Media acquisition&lt;/font&gt;&lt;/p&gt;
&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font size="1"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom" align="right"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;28,681&lt;/font&gt;&lt;/td&gt;
&lt;td nowrap="nowrap" valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr style="font-size:1px"&gt;
&lt;td valign="bottom"&gt;&lt;/td&gt;
&lt;td valign="bottom"&gt;&amp;#xA0;&amp;#xA0;&lt;/td&gt;
&lt;td valign="bottom"&gt;
&lt;p style="border-top:1px solid #000000"&gt;&amp;#xA0;&lt;/p&gt;
&lt;/td&gt;
&lt;td valign="bottom"&gt;
&lt;p style="border-top:1px solid #000000"&gt;&amp;#xA0;&lt;/p&gt;
&lt;/td&gt;
&lt;td&gt;&amp;#xA0;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td valign="top"&gt;
&lt;p style="margin-left:1.00em; text-indent:-1.00em"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;Balance, as of
April&amp;#xA0;30, 2013, net&lt;/font&gt;&lt;/p&gt;
&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font size="1"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;$&lt;/font&gt;&lt;/td&gt;
&lt;td valign="bottom" align="right"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;141,833&lt;/font&gt;&lt;/td&gt;
&lt;td nowrap="nowrap" valign="bottom"&gt;&lt;font style="font-family:Times New Roman" size="2"&gt;&amp;#xA0;&amp;#xA0;&lt;/font&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr style="font-size:1px"&gt;
&lt;td valign="bottom"&gt;&lt;/td&gt;
&lt;td valign="bottom"&gt;&amp;#xA0;&amp;#xA0;&lt;/td&gt;
&lt;td valign="bottom"&gt;
&lt;p style="border-top:3px double #000000"&gt;&amp;#xA0;&lt;/p&gt;
&lt;/td&gt;
&lt;td valign="bottom"&gt;
&lt;p style="border-top:3px double #000000"&gt;&amp;#xA0;&lt;/p&gt;
&lt;/td&gt;
&lt;td&gt;&amp;#xA0;&lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;
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