Changes in the carrying amount of goodwill for the six months ended June 30, 2021 were as follows (in millions):


	Google Services		Google Cloud		Other Bets		Total
Balance as of December 31, 2020	$	18,517	$	1,957	$	701	$	21,175
Acquisitions	1,221		5		1		1,227
Foreign currency translation and other adjustments	13		1		(10)		4
Balance as of June 30, 2021	$	19,751	$	1,963	$	692	$	22,406

Information regarding purchased intangible assets were as follows (in millions):


	As of December 31, 2020
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Patents and developed technology	$	4,639	$	3,649	$	990
Customer relationships	266		49		217
Trade names and other	699		461		238
Total	$	5,604	$	4,159	$	1,445


	As of June 30, 2021
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Patents and developed technology	$	4,824	$	3,927	$	897
Customer relationships	464		93		371
Trade names and other	861		503		358
Total	$	6,149	$	4,523	$	1,626

For all intangible assets acquired and purchased during the six months ended June 30, 2021, patents and developed technology have a weighted-average useful life of 4.0 years, customer relationships have a weighted-average useful life of 3.8 years, and trade names and other have a weighted-average useful life of 10.0 years.

Amortization expense relating to purchased intangible assets was $194 million and $215 million for the three months ended June 30, 2020 and 2021, respectively, and $398 million and $432 million for the six months ended June 30, 2020 and 2021, respectively.

As of June 30, 2021, expected amortization expense relating to purchased intangible assets for each of the next five years and thereafter was as follows (in millions):


Remainder of 2021	$	430
2022	507
2023	226
2024	197
2025	74
Thereafter	192
Total	$	1,626