The amount of share-based compensation expense recognized by the Company by location in its statements of operations for the years ended December 31, 2018, 2017 and 2016 is as follows (in thousands):

	Year ended December 31,
	2018		2017		2016
Cost of revenues	$	21	$	18	$	5
Sales and marketing		926		141		49
General and administrative		646		226		70
Research and development		150		111		37
Total	$	1,743	$	496	$	161

In June 2018, the Company adopted the 2018 Equity Incentive Plan, or 2018 Plan, which authorized the issuance of up to 1.4 million shares in the form of restricted stock, stock appreciation rights and stock options to the Company’s directors, employees and consultants. The amount and terms of grants are determined by the Company’s board of directors. All stock options granted to date have had exercise prices equal to the fair value, as determined by the closing price as reported by the Nasdaq Global Market on the date of grant, of the underlying common stock on the date of grant. The contractual term of stock options is up to 10 years, and stock options are exercisable in cash or as otherwise determined by the board of directors. Generally, stock options vest 25% upon the first anniversary of the date of grant and the remainder ratably monthly thereafter for 36 months. As of December 31, 2018, there were 1.3 million shares available for future issuance under the 2018 Plan.

In April 2003 (and as subsequently amended), the Company adopted the 2003 Stock Incentive Plan, or 2003 Plan, which authorized the issuance of up to 3.1 million shares in the form of restricted stock, stock appreciation rights and stock options to the Company’s directors, employees and consultants. The amount and terms of grants are determined by the Company’s board of directors. All stock options granted to date have had exercise prices equal to the estimated fair value, as determined by the board of directors, of the underlying common stock on the date of the grant. The contractual term of stock options is up to 10 years, and stock options are exercisable in cash or as otherwise determined by the board of directors. Generally, stock options vest 25% upon the first anniversary of the date of grant and the remainder ratably monthly thereafter for 36 months. As of December 31, 2018, there were no shares available for future issuance under the 2003 Plan. As of the closing of the IPO, all shares available for issuance under the 2003 Plan were carried over to the newly adopted 2018 Plan.

The following table summarizes the Company’s stock option activity for the years ended December 31, 2018, 2017 and 2016:

	Number of Shares under Option (in thousands)			Weighted- average Exercise Price per Option		Weighted- average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2015		1,767		$	2.52
Granted		255		$	2.45
Exercised		(19	)	$	3.58
Forfeited		(161	)	$	5.68
Expired		(16	)	$	19.63
Outstanding at December 31, 2016		1,826		$	2.07
Granted		967		$	3.03
Exercised		(33	)	$	1.05
Forfeited		(316	)	$	2.66
Outstanding at December 31, 2017		2,444		$	2.39
Granted		584		$	8.33
Exercised		(194	)	$	2.60
Forfeited		(123	)	$	3.73
Outstanding at December 31, 2018		2,711		$	3.59		7.3	$	42,773
Exercisable at December 31, 2018		1,613		$	2.22		6.2	$	27,921
Vested and expected to vest at December 31, 2018		2,711		$	3.59		7.3	$	42,773

The Company recognized share-based compensation expense related to stock options of $1.6 million, $0.4 million and $0.2 million for the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, there was $3.1 million of total unrecognized compensation cost related to non-vested stock options which the Company expects to recognize over a weighted-average period of 3.1 years. The weighted-average grant-date fair value of stock options granted during the years ended December 31, 2018, 2017 and 2016 was estimated at $5.03, $1.45 and $1.16 per option. The total intrinsic value of stock options exercised during the years ended December 31, 2018, 2017 and 2016 was $3.3 million, $0.1 million and de minimis, respectively.

For the years ended December 31, 2018, 2017 and 2016, the grant-date fair value of stock options was estimated at the time of grant using the following weighted-average inputs and assumptions in the Black-Scholes option pricing model:

	2018			2017			2016
Estimated fair value of common stock	$	8.41		$	2.90		$	2.32
Exercise price	$	8.41		$	2.90		$	2.32
Expected term (in years)		6.0			6.0			6.0
Risk-free interest rate		2.7	%		2.0	%		1.4	%
Expected volatility		65.3	%		48.0	%		44.2	%
Dividend yield		0	%		0	%		0	%

In April 2018, the Company’s board of directors granted options to purchase 54,794 shares of common stock to the members of the board. These options have an exercise price of $5.22 and vest in 12 equal monthly installments beginning in March 2018; however, the entire grant was subject to forfeiture if an initial public offering of the Company’s common stock did not occur by December 31, 2018. The estimated grant-date fair value of the options awards was $0.2 million. Upon the closing of the IPO on July 2, 2018, the Company recognized the fair value of the vested portion of the awards as share-based compensation expense, with the unvested portion to be recognized as share-based compensation expense ratably over the remaining service period.

The following table summarizes the Company’s restricted stock award and restricted stock unit activity for the years ended December 31, 2018, 2017 and 2016:

	Non-vested Restricted Stock Awards (in thousands)			Weighted- average Grant-date Fair Value		Non-vested Restricted Stock Units (in thousands)		Weighted- average Grant-date Fair Value
Non-vested at December 31, 2015		-		$	-		-	$	-
Granted		42		$	2.03		-	$	-
Vested		(20	)	$	2.03		-	$	-
Non-vested at December 31, 2016		22		$	2.03		-	$	-
Granted		11		$	4.06		-	$	-
Vested		(17	)	$	2.90		-	$	-
Non-vested at December 31, 2017		16		$	2.32		-	$	-
Granted		-		$	-		43	$	25.21
Vested		(12	)	$	2.32		-	$	25.92
Non-vested at December 31, 2018		4		$	2.32		43	$	25.21

The Company recognized share-based compensation expense related to restricted stock awards and restricted stock units of $0.2 million, $0.1 million and de minimis during the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, there was $0.9 million of unrecognized compensation cost related to non-vested restricted stock awards and restricted stock units which the Company expects to recognize over a weighted-average period of 3.4 years. The total fair value at the vesting date of restricted stock awards and restricted stock units vested during the years ended December 31, 2018, 2017 and 2016 was $0.2 million, $0.1 million and de minimis, respectively.