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”). In January 2017, our board of directors adopted the 2017 Plan, and in February 2017 our stockholders approved the 2017 Plan, effective on March 1, 2017, which 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, 2020:

	Class A Outstanding			Weighted- Average Grant Date Fair Value
	(in thousands, except per share data)
Unvested at December 31, 2019		148,797		$	12.39
Granted		45,118		$	15.04
Vested		(36,051	)	$	13.46
Forfeited		(4,892	)	$	12.83
Unvested at June 30, 2020		152,972		$	12.91

RSUs granted to employees before January 1, 2017 (“Pre-2017 Awards”) included both service-based and performance conditions to vest in the underlying common stock. The performance condition related to Pre-2017 Awards was satisfied on the effectiveness of the registration statement for our IPO, which occurred in March 2017. Total unrecognized compensation cost related to Pre-2017 Awards was $6.6 million as of June 30, 2020 and is expected to be recognized over a weighted-average period of 0.4 years.

All RSUs and RSAs granted after December 31, 2016 vest on the satisfaction of only a service-based condition (“Post-2017 Awards”). Total unrecognized compensation cost related to Post-2017 Awards was $1.7 billion as of June 30, 2020 and is expected to be recognized over a weighted-average period of 2.9 years. The service condition for Post-2017 Awards 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 Post-2017 Awards with vesting periods in excess of four years. The service condition for Post-2017 Awards granted after February 2018 is generally satisfied in equal monthly or quarterly installments over four years.

Additionally, we had 4.0 million and 9.4 million RSUs that were vested but have not yet settled as of June 30, 2020 and December 31, 2019, respectively. These RSUs are primarily related to the CEO award.

The following table summarizes the stock option award activity under the Stock Plans during the six months ended June 30, 2020:

	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, 2019		8,712			1,550		$	9.00		5.59	$	75,460
Granted		2			—		$	17.83		—	$	—
Exercised		(2,744	)		(393	)	$	7.52		—	$	—
Forfeited		(119	)		—		$	13.17		—	$	—
Outstanding at June 30, 2020		5,851			1,157		$	9.60		5.22	$	97,375

Total unrecognized compensation cost related to unvested stock options was $11.1 million as of June 30, 2020 and is expected to be recognized over a weighted-average period of 1.8 years.

	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(in thousands)
Cost of revenue	$	2,066	$	1,786	$	3,848	$	3,635
Research and development		127,516		132,610		245,833		244,852
Sales and marketing		27,107		26,474		51,913		44,234
General and administrative		29,482		34,704		56,626		65,409
Total	$	186,171	$	195,574	$	358,220	$	358,130