Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Revenue for the years ended December 31, 2012, 2011, and 2010 consists of the following (in millions):



	Year Ended December 31,
	2012		2011		2010
Advertising	$	4,279	$	3,154	$	1,868
Payments and other fees	810		557		106
Total revenue	$	5,089	$	3,711	$	1,974

Estimated useful lives of property and equipment

The estimated useful lives of property and equipment are described below:



Property and Equipment		Useful Life
Network equipment		Three to four years
Buildings		15 to 20 years
Computer software, office equipment and other		Two to five years
Leased equipment and leasehold improvements		Lesser of estimated useful life or remaining lease term

Deferred revenue and deposits

Deferred Revenue and Deposits

Deferred revenue consists of billings in advance of revenue recognition. Deposits relate to unused virtual currency held by our users. Once this virtual currency is utilized by a user, approximately 70% of this amount would then be payable to the Platform developer and the balance would be recognized as revenue.

Deferred revenue and deposits consists of the following (in millions):



	December 31,
	2012		2011
Deferred revenue	$	8	$	75
Deposits	22		15
Total deferred revenue and deposits	$	30	$	90