Table:
|  | December 31, 2019 | December 31, 2018 |
| --- | --- | --- |
| Deferred revenue: |  |  |
| Products | $6,593 | $5,216 |
| Services | 94,571 | 92,750 |
| Total deferred revenue | 101,164 | 97,966 |
| Less: current portion | (62,233) | (63,874) |
| Non-current portion | $38,931 | $34,092 |
Paragraphs:
Deferred revenue primarily consists of amounts that have been invoiced but not yet been recognized as revenue and consists of performance obligations pertaining to support and subscription services. During the years ended December 31, 2019 and 2018, we recognized revenue of $63.2 million and $60.2 million, related to deferred revenue at the beginning of the period.
Deferred revenue consisted of the following (in thousands):
Question:
What does deferred revenue refer to?
Answer: Deferred revenue primarily consists of amounts that have been invoiced but not yet been recognized as revenue and consists of performance obligations pertaining to support and subscription services