Goodwill represents the difference between the purchase price and the estimated fair value of identifiable assets acquired and liabilities assumed. We are required to perform impairment tests related to our goodwill annually, which we perform during the third quarter of each fiscal year, or when we identify certain triggering events or circumstances that would more likely than not reduce the estimated fair value of the goodwill below its carrying amount. The following table represents the changes in goodwill since January 31, 2019:

Intangible assets, net, consisted of the following at April 30, 2019:

As a result of our impairment analysis in the fourth quarter of fiscal 2019, the carrying value of our intangible assets was zero as of January 31, 2019.

We recognized amortization expense of intangible assets in cost of revenue and operating expense categories as follows:

Future estimated amortization expense of acquired intangibles as of April 30, 2019 is as follows: