We grant restricted stock units ("RSUs") with a service condition, and RSUs with market and service conditions ("MSUs").

The following table summarizes activity for RSUs and MSUs for the nine months ended September 30, 2024 (in thousands):


	Number of Underlying Shares
	RSUs			MSUs
Outstanding at December 31, 2023		1,078			174
Granted		426			165
Vested		(408	)		(98	)
Forfeited		(109	)		(2	)
Outstanding at September 30, 2024		987			239

The following table presents the detail of stock-based compensation expense amounts included in our condensed consolidated statements of operations for the periods presented (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Cost of revenue	$	521	$	489	$	1,508	$	1,378
Research and development expense		6,813		5,446		18,618		15,894
Sales and marketing expense		2,743		2,652		7,954		7,581
General and administrative expense		4,764		3,720		13,256		10,826
Total stock-based compensation expense	$	14,841	$	12,307	$	41,336	$	35,679