Balance Sheet Components

12 Months Ended

Dec. 31, 2017

5. Balance Sheet Components

The following table shows the components of property and equipment as of the dates presented:

		December 31,
	Estimated Useful Life	2017			2016
Computer equipment	3 years	$	29,938		$	28,905
Software, including internally developed software	3 years		23,389			21,323
Leasehold improvements	Shorter of useful life or lease term		4,617			4,613
Office equipment, furniture and fixtures	3 to 5 years		2,127			2,284
			60,071			57,125
Less: Accumulated depreciation and amortization			(44,512	)		(36,544	)
		$	15,559		$	20,581

Depreciation and amortization of internally developed software for 2017, 2016 and 2015 was $8,427, $9,023, and $9,543, respectively.

The following table shows the components of accrued expenses and other current liabilities as of the dates presented:

	December 31,
	2017		2016
Accrued salary and payroll-related expenses	$	4,372	$	3,894
Accrued accounts payable		2,161		1,915
Customer advances		2,003		1,582
Deferred rent		475		408
Sales and use tax payable		341		210
Income taxes payable		142		—
Other		521		353
	$	10,015	$	8,362