Condensed Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Costs and expenses:
Amortization adjustment	$ 17	$ 18
Stock-based compensation:
Stock-based compensation	29	26
Selling and Marketing
Stock-based compensation:
Stock-based compensation	4	4
Technology and Content
Stock-based compensation:
Stock-based compensation	12	11
General and Administrative
Stock-based compensation:
Stock-based compensation	13	11
Acquired Technology
Costs and expenses:
Amortization of intangible assets	1	1
Website Development Costs
Costs and expenses:
Depreciation	$ 16	$ 17

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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