The changes in the carrying amount of goodwill for the years ended December 31, 2023 and 2022 were as follows:


	Goodwill
	(in thousands)
Balance as of December 31, 2021	$	1,588,452
Goodwill acquired	69,291
Foreign currency translation	(11,623)
Balance as of December 31, 2022	$	1,646,120
Goodwill acquired	42,780
Foreign currency translation	2,927
Balance as of December 31, 2023	$	1,691,827


	December 31, 2023
	Weighted- Average Remaining Useful Life - Years	Gross Carrying Amount		Accumulated Amortization		Net

	(in thousands, except years)
Domain names	3.0	$	745	$	(546)	$	199
Technology	2.8	323,313		(197,608)		125,705
Patents	8.8	39,373		(19,099)		20,274
Other	—	6,000		(5,875)		125
		$	369,431	$	(223,128)	$	146,303


	December 31, 2022
	Weighted- Average Remaining Useful Life - Years	Gross Carrying Amount		Accumulated Amortization		Net

	(in thousands, except years)
Domain names	4.0	$	954	$	(690)	$	264
Trademarks	1.2	800		(478)		322
Technology	3.1	340,375		(178,427)		161,948
Customer relationships	5.7	21,000		(6,641)		14,359
Patents	9.1	39,373		(14,912)		24,461
Other	1.0	6,000		(2,874)		3,126
		$	408,502	$	(204,022)	$	204,480

Amortization of intangible assets for the years ended December 31, 2023, 2022, and 2021 was $81.1 million, $132.3 million, and $63.2 million, respectively. In 2023, we recognized $19.9 million in charges related to the revision of the useful lives and disposal of certain acquired intangible assets. In 2022, we revised the useful lives of certain customer relationships, trademarks, domain names, and technology, which resulted in a $49.3 million increase to amortization expense for the year ended December 31, 2022.

As of December 31, 2023, the estimated intangible asset amortization expense for the next five years and thereafter is as follows:


	Estimated Amortization
	(in thousands)
Year ending December 31,
2024	$	58,532
2025	42,513
2026	20,776
2027	12,104
2028	4,323
Thereafter	8,055
Total	$	146,303