Under the 2016 Equity and Incentive Compensation Plan Amended and Restated as of June 13, 2019 (the "2016 Equity Plan"), we may grant incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units, other stock awards and cash incentive awards to employees, directors and consultants. We maintain other stock-based compensation plans including the 2008 Equity Incentive Plan (the “2008 Equity Plan”), under which no additional grants may be made.

In connection with the acquisition of Convio in May 2012, we maintain the Convio, Inc. 1999 Stock Option/Stock Issuance Plan, as amended (the “Convio 1999 Plan”) and Convio, Inc. 2009 Stock Incentive Plan, as amended (the “Convio 2009 Plan”), which we assumed upon the acquisition of Convio. Our Compensation Committee of the Board of Directors administers all of these plans and the stock-based awards are granted under terms determined by them.

The total number of authorized stock-based awards available under our plans was 4,779,951 as of December 31, 2020. We issue common stock from our pool of authorized stock upon exercise of stock options and stock appreciation rights, vesting of restricted stock units or upon granting of restricted stock.

Historically, we have issued four types of awards under these plans: restricted stock awards, restricted stock units, stock options and stock appreciation rights ("SARs"). There have been no new stock options or SARs granted since 2005 and 2013, respectively. The following table sets forth the number of awards outstanding for each award type as of:

The majority of the stock-based awards granted under these plans have a 10-year contractual term. Awards granted to our executive officers and certain members of management are subject to accelerated vesting upon a change in control as defined in the employees’ retention agreement.

We recognize compensation expense associated with stock options and awards with performance or market based vesting conditions on an accelerated basis over the requisite service period of the individual grantees, which generally equals the vesting period. We recognize compensation expense associated with restricted stock awards and SARs on a straight-line basis over the requisite service period of the individual grantees, which generally equals the vesting period. We recognize the effect of awards for which the requisite service period is not rendered when the award is forfeited (that is, we recognize the effect of forfeitures in compensation cost when they occur). Previously recognized compensation cost for an award is reversed in the period that the award is forfeited.

Stock-based compensation expense is allocated to cost of revenue and operating expenses on the consolidated statements of comprehensive income based on where the associated employee’s compensation is recorded. The following table summarizes stock-based compensation expense:


	Years ended December 31,
(in thousands)	2020		2019		2018
Included in cost of revenue:
Cost of recurring	$	5,793	$	1,879	$	2,464
Cost of one-time services and other	7,581		1,487		2,778
Total included in cost of revenue	13,374		3,366		5,242
Included in operating expenses:
Sales, marketing and customer success	15,514		11,203		9,285
Research and development	18,527		11,115		9,048
General and administrative	39,842		32,949		24,699
Total included in operating expenses	73,883		55,267		43,032
Total stock-based compensation expense	$	87,257	$	58,633	$	48,274

The total amount of compensation cost related to unvested awards not recognized was $98.7 million at December 31, 2020. It is expected that this amount will be recognized over a weighted average period of 1.4 years.

We have granted shares of common stock subject to certain restrictions under the 2016 Equity Plan and the 2008 Equity Plan. Restricted stock awards granted to employees vest in equal annual installments generally over 4 years from the grant date subject to the recipient’s continued employment with us. Restricted stock awards granted to non-employee directors vest after one year from the date of grant or, if earlier, immediately prior to the next annual election of directors, provided the non-employee director is serving as a director at that time. The fair market value of the stock at the time of the grant is amortized on a straight-line basis to expense over the period of vesting. Recipients of restricted stock awards have the right to vote such shares and receive dividends, if declared.


Restricted stock awards	Restricted stock awards	Weighted average grant-date fair value		Weighted average remaining contractual term (in years)	Aggregate intrinsic value(1) (in thousands)
Unvested at January 1, 2020	1,316,764	$	79.92
Granted	657,718	77.16
Vested	(520,296)	76.66
Forfeited	(177,077)	80.71
Unvested at December 31, 2020	1,277,109	79.54		8.4	$	73,510

The total fair value of restricted stock awards that vested during the years ended December 31, 2020, 2019 and 2018 was $39.9 million, $37.5 million and $24.2 million, respectively. The weighted average grant-date fair value of restricted stock awards granted during the years ended December 31, 2019 and 2018 was $78.39 and $94.51, respectively.

We have also granted restricted stock units subject to certain restrictions under the 2016 Equity Plan and the 2008 Equity Plan. Restricted stock units granted to employees vest in equal annual installments generally over 3 years from the grant date subject to the recipient’s continued employment with us. We have also granted restricted stock units for which vesting is subject to meeting certain performance and/or market conditions. Restricted stock units granted with a market condition had a fair market value assigned at the grant date based on the use of a Monte Carlo simulation model. The fair market value of the stock at the time of the grant is amortized to expense on a straight-line basis over the period of vesting except for awards with market or performance conditions, which are amortized on an accelerated basis over the period of vesting.


Restricted stock units	Restricted stock units	Weighted average grant-date fair value		Weighted average remaining contractual term (in years)	Aggregate intrinsic value(1) (in thousands)
Unvested at January 1, 2020	501,487	$	80.49
Granted	1,020,381	59.59
Forfeited	(111,450)	67.75

Vested	(239,533)	78.97
Unvested at December 31, 2020	1,170,885	63.62		9.0	$	67,396

The total fair value of restricted stock units that vested during the years ended December 31, 2020, 2019 and 2018 was $18.9 million, $19.2 million, and $13.7 million, respectively. The weighted average grant date fair value of restricted stock units granted for the years ended December 31, 2019 and 2018 was $77.90 and $95.59, respectively.

All SARs previously granted were fully vested as of December 31, 2017. The total intrinsic value of SARs exercised during the years ended December 31, 2019 and 2018 was $3.6 million and $12.4 million, respectively. SARs granted with a market condition had a fair market value assigned at the grant date based on the use of a Monte Carlo simulation model. All other SARs granted had a fair market value assigned at the grant date based on the use of the Black-Scholes option pricing model.