Selected quarterly financial information for 2017 and 2016 is as follows:



	Quarter Ended
	Dec. 31, 2017			Sept. 30, 2017			Jun. 30, 2017			Mar. 31, 2017			Dec. 31, 2016			Sept. 30, 2016			Jun. 30, 2016			Mar. 31, 2016

	(unaudited, in thousands, except per share data)
Revenue	$	55,403		$	50,081		$	47,727		$	47,014		$	44,207		$	40,982		$	38,886		$	38,015
Cost of revenue ⁽¹⁾⁽²⁾	22,363			20,497			20,273			19,971			15,770			17,790			16,764			16,610
Gross profit	33,040			29,584			27,454			27,043			28,437			23,192			22,122			21,405
Operating expenses:
Research and development ⁽¹⁾⁽²⁾	6,748			6,689			6,836			6,847			6,236			6,041			5,799			5,802
Sales and marketing ⁽¹⁾⁽²⁾	17,358			16,502			16,932			15,778			14,480			12,925			12,637			12,706
General and administrative ⁽¹⁾⁽²⁾	8,767			4,679			6,845			8,860			6,511			6,143			5,882			6,536
Total operating expenses	32,873			27,870			30,613			31,485			27,227			25,109			24,318			25,044
Loss from operations	167			1,714			(3,159		)	(4,442		)	1,210			(1,917		)	(2,196		)	(3,639		)
Other income (expense), net:
Extinguishment of debt	—			—			—			—			—			(1,026		)	—			—
Interest expense	(836		)	(865		)	(888		)	(882		)	(869		)	(961		)	(1,197		)	(1,199		)
Interest income and other	164			118			90			118			54			12			(33		)	(45		)
Total other income (expense), net	(672		)	(747		)	(798		)	(764		)	(815		)	(1,975		)	(1,230		)	(1,244		)
Income (loss) before income taxes	(505		)	967			(3,957		)	(5,206		)	395			(3,892		)	(3,426		)	(4,883		)
Provision for (benefit from) income taxes	126			43			50			49			(14		)	(2		)	42			28
Net income (loss)	$	(631	)	$	924		$	(4,007	)	$	(5,255	)	$	409		$	(3,890	)	$	(3,468	)	$	(4,911	)
Net income (loss) per share:
Basic	$	(0.01	)	$	0.02		$	(0.07	)	$	(0.10	)	$	0.01		$	(0.07	)	$	(0.07	)	$	(0.10	)
Diluted	$	(0.01	)	$	0.02		$	(0.07	)	$	(0.10	)	$	0.01		$	(0.07	)	$	(0.07	)	$	(0.10	)
Shares used in computing net loss per share:
Basic	56,034			55,310			54,723			53,688			53,126			52,708			52,143			51,377
Diluted	56,034			59,441			54,723			53,688			56,633			52,708			52,143			51,377

(1) Included stock-based compensation as follows:



	Quarter Ended
	Dec. 31, 2017		Sept. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sept. 30, 2016		Jun. 30, 2016		Mar. 31, 2016

	(unaudited, in thousands)
Cost of revenue	$	594	$	599	$	575	$	434	$	424	$	357	$	329	$	265
Research and development	807		797		801		637		549		547		528		435
Sales and marketing	1,128		1,084		1,224		928		759		626		544		434
General and administrative	2,111		1,240		1,254		1,130		984		989		1,013		860
Total stock-based compensation	$	4,640	$	3,720	$	3,854	$	3,129	$	2,716	$	2,519	$	2,414	$	1,994

(2) Included depreciation and amortization expenses as follows:



	Quarter Ended
	Dec. 31, 2017		Sept. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sept. 30, 2016		Jun. 30, 2016		Mar. 31, 2016

	(unaudited, in thousands)
Cost of revenue	$	1,611	$	1,397	$	1,716	$	1,576	$	1,608	$	1,668	$	1,616	$	1,680
Research and development	170		182		237		206		224		204		161		148
Sales and marketing	30		30		30		30		58		56		54		53
General and administrative	257		272		287		283		196		212		229		222
Total depreciation and amortization	$	2,068	$	1,881	$	2,270	$	2,095	$	2,086	$	2,140	$	2,060	$	2,103