5. Balance Sheet Components

Property and Equipment, Net

Property and equipment consist of the following (in thousands):

	June 30, 2018			December 31, 2017
Software	$	38,275		$	33,198
Computer equipment		24,138			24,342
Leasehold improvements		7,827			7,905
Furniture and fixtures		2,079			2,107
Total		72,319			67,552
Accumulated depreciation and amortization		(58,246	)		(55,752	)
Projects in process		1,132			4,810
Property and equipment, net	$	15,205		$	16,610

Depreciation and amortization expense related to property and equipment was $1.9 million and $1.6 million for the three months ended June 30, 2018 and 2017, respectively, and $3.5 million and $3.7 million for the six months ended June 30, 2018 and 2017, respectively.

The Company capitalized internal use software development and enhancement costs of $0.7 million and $1.6 million during the three and six months ended June 30, 2018, respectively, and $1.1 million and $2.1 million during the three and six months ended June 30, 2017, respectively. During the three and six months ended June 30, 2018, the Company had $0.4 million respectively in amortization expense related to internal use software, which is included in property and equipment depreciation and amortization expense above and recorded as cost of revenues, as compared to zero and $0.6 million, respectively, during the comparable period of 2017. The unamortized capitalized development and enhancement costs were $5.6 million and $4.4 million as of June 30, 2018 and December 31, 2017, respectively.

Accrued Compensation and Benefits

Accrued compensation and benefits consist of the following (in thousands):

	June 30, 2018		December 31, 2017
Bonus	$	4,260	$	7,212
Commissions		3,229		4,199
Vacation		467		371
Payroll and related expenses		1,645		2,132
Accrued compensation and benefits	$	9,601	$	13,914

Other Current Liabilities

Other current liabilities consist of the following (in thousands):

	June 30, 2018		December 31, 2017
Distribution fees	$	17,151	$	18,485
Marketing expenses		1,495		2,826
Prefunded liability		1,580		2,151
Traffic acquisition cost		3,526		3,040
Amounts owed for certain exclusive rights		6,500		—
Other		11,099		9,036
Other current liabilities	$	41,351	$	35,538