16. COST OF REVENUE

Cost of revenue principally includes payroll and employee benefits associated with personnel employed in customer service and operations roles, fees paid to external providers related to provision of services, reimbursable expenses, technology and telecommunications expenses as well as depreciation and amortization of operating assets. The components of cost of revenue were as follows for the years ended December 31:

(in thousands)	2013		2012		2011

Compensation and benefits	$	156,812	$	113,145	$	82,548
Outside fees and services	193,233		123,338		86,201
Reimbursable expenses	102,478		96,147		82,074
Technology and telecommunications	25,534		23,404		18,772
Depreciation and amortization	14,423		10,167		6,254

Total	$	492,480	$	366,201	$	275,849