We maintain three share-based employee compensation plans: the 2017 Equity Incentive Plan (“2017 Plan”), the 2014 Equity Incentive Plan (“2014 Plan”), and the 2012 Equity Incentive Plan (“2012 Plan”, and collectively with the 2017 Plan and the 2014 Plan, the “Stock Plans”). The 2017 Plan serves as the successor to the 2014 Plan and 2012 Plan and provides for the grant of incentive stock options to employees, including employees of any parent or subsidiary, and for the grant of nonstatutory stock options, stock appreciation rights, RSAs, RSUs, performance stock awards, performance cash awards, and other forms of stock awards to employees, directors, and consultants, including employees and consultants of our affiliates.

The following table summarizes the RSU and RSA activity during the six months ended June 30, 2022:

	Class A Outstanding			Weighted- Average Grant Date Fair Value
	(in thousands, except per share data)
Unvested at December 31, 2021		86,180		$	26.07
Granted		39,762		$	23.54
Vested		(25,744	)	$	20.44
Forfeited		(5,875	)	$	26.77
Unvested at June 30, 2022		94,323		$	26.50

All RSUs and RSAs vest on the satisfaction of a service-based condition. Total unrecognized compensation cost related to outstanding RSUs and RSAs was $2.3 billion as of June 30, 2022 and is expected to be recognized over a weighted-average period of 2.1 years. The service condition for RSUs and RSAs granted prior to February 2018 is generally satisfied over four years, 10% after the first year of service, 20% over the second year, 30% over the third year, and 40% over the fourth year. In limited instances, we have issued RSUs with vesting periods in excess of four years. The service condition for RSUs and RSAs granted after February 2018 is generally satisfied in equal monthly or quarterly installments over three to four years.

The following table summarizes the stock option award activity under the Stock Plans during the six months ended June 30, 2022:

	Class A Number of Shares			Class B Number of Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value⁽¹⁾
	(in thousands, except per share data)
Outstanding at December 31, 2021		3,676			628		$	10.59		4.19	$	157,374
Granted		—			—		$	—		—	$	—
Exercised		(260	)		(10	)	$	13.60		—	$	—
Forfeited		(12	)		—		$	20.50		—	$	—
Outstanding at June 30, 2022		3,404			618		$	10.36		3.64	$	16,111

Total unrecognized compensation cost related to unvested stock options was $0.6 million as of June 30, 2022 and is expected to be recognized over a weighted-average period of 2.2 years.

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
	(in thousands)
Cost of revenue	$	2,849	$	2,847	$	5,295	$	5,503
Research and development		221,650		174,491		404,516		338,284
Sales and marketing		48,577		37,491		90,648		66,575
General and administrative		45,734		41,771		93,795		83,311
Total	$	318,810	$	256,600	$	594,254	$	493,673