The following table summarizes revenue from contracts with customers for the three and nine months ended September 30, 2020 and September 30, 2019 (in thousands):

	Three months ended September 30, 2020		Three months ended September 30, 2019		Nine months ended September 30, 2020		Nine months ended September 30, 2019
eDiscovery services	$	48,021	$	52,910	$	147,056	$	161,075
Managed review		14,015		14,025		36,847		35,944
Legal technology services		62,036		66,935		183,903		197,019
Data recovery		10,265		11,234		31,050		34,508
Total revenue	$	72,301	$	78,169	$	214,953	$	231,527

We primarily sell services and products that fall into the categories discussed below. Each category contains one or more performance obligations that are either (1) capable of being distinct (i.e., the customer can benefit from the product or service on its own or together with readily available resources, including those purchased separately from us) and distinct within the context of the contract (i.e., separately identified from other promises in the contract) or (2) a series of distinct products or services that are substantially the same and have the same pattern of transfer to the customer.

We generate the majority of our revenues by providing Legal Technology services to our clients. All of our eDiscovery service contracts are time and materials types of arrangements.

Time and materials arrangements are based on units of data stored or processed. Unit-based revenues are recognized as services are provided, based on either the amount of data stored or processed, the number of concurrent users accessing the information or the number of pages or images processed for a client, at agreed upon per unit rates. We recognize revenues for these arrangements utilizing a right-to-invoice practical expedient because we have a right to consideration for services completed to date.

Certain of our eDiscovery contracts are subscription-based, fixed fee arrangements, which have tiered pricing based on the quantity of data hosted. For a fixed monthly fee, our clients receive a variety of optional eDiscovery services, which are included in addition to the data hosting. We recognize revenues for these arrangements based on predetermined monthly fees as determined in our contractual agreements, utilizing a right-to-invoice practical expedient because we have a right to consideration for services completed to date.

Managed review services are time and materials types of arrangements. These agreements require the client to pay us based on the number of hours worked at contractually agreed-upon rates. We recognize revenues for these arrangements based on hours incurred and contracted rates utilizing a right-to-invoice practical expedient because we have a right to consideration for services completed to date.

Data recovery services are mainly fixed fee arrangements requiring the client to pay a pre-established fee in exchange for the successful completion of a data recovery on a predetermined device. For the recovery services performed by the Company’s technicians, the revenue is recognized at a point in time, when the recovered data is sent to the customer.

Data erasure services are fixed fee arrangements for which revenue is recognized at a point in time, when the certificate of erasure is sent to the customer.

Ontrack PowerControls offers term license subscriptions for customers with on-premises installations of the software pursuant to contracts that are historically one to four years in length. The term license subscriptions include maintenance, support, as well as access to future software upgrades and fixes. The license and the additional support services are deemed to be one performance obligation, and thus revenue for these arrangements is recognized ratably over the term of the agreement.