Table:
| Years Ended December 31, |  |  |  |
| --- | --- | --- | --- |
| (In thousands) | 2019 | 2018 | 2017 |
| Net cash provided by operations | $ 13,951 | $ 16,671 | $ 18,204 |
| Net cash used in investing activities | $ (296,243 ) | $ (15,952 ) | $ (11,285 ) |
| Net cash provided by (used in) financing activities | $ 268,740 | $ (6,593 ) | $ (367 ) |
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Sources and Uses of Cash
Our primary source of liquidity from operations was the collection of revenue in advance from our customers, accounts receivable from our customers, and the management of the timing of payments to our vendors and service providers.
Investing activities in 2019 consist of $284.6 million, net of cash acquired, used in the acquisitions of AppRiver and DeliverySlip and $11.7 million for capital expenditures, which include $8.2 million in internal-use software costs, and $3.5 million for computer and networking equipment. These investments in new equipment and cloud hosting infrastructure are to renovate our business processes and product offerings.
Investing activities in 2018 consist of $11.8 million, net of cash acquired, used in the acquisition of Erado and $4.2 million for capital expenditures, which include $2.1 million for computer and networking equipment, $1.5 million in internal-use software costs, and $500 thousand for other activities including the acquisition of other internal use software. These investments in new equipment and cloud hosting infrastructure were to modernize our business processes and product offerings.
Financing activities in 2019 includes proceeds from long term debt of $179.2 million, net of issuance costs of $6.4 million and repayment of $1.4 million, as well as $96.6 million, net of issuance costs, raised through the private purchase of preferred stock, and $415 thousand received from the exercise of stock options. The proceeds from our debt and preferred stock issuances were used to fund our AppRiver acquisition in February 2019 and our DeliverySlip acquisition in May 2019. We also used $3.8 million for contingent consideration payments associated with our acquisitions of Greenview, Erado and DeliverySlip. In addition to these items, we paid $1.7 million to satisfy finance lease liabilities and $1.9 million to repurchase common stock related to the tax impact of vesting restricted awards in 2019.
Financing activities in 2018 relate primarily to $5.4 million used in a $10 million share repurchase program authorized by our Board of Directors on April 24, 2017, and $656 thousand used in the repurchase of common stock related to the tax impact of vesting restricted stock awards, and a $605 thousand earn-out payment associated with our acquisition of Greenview. Financing activities in 2017 include $3.8 million used in the same share repurchase program and $762 thousand used in the repurchase of common stock related to the tax impact of vesting restricted awards offset by the receipt of $4.2 million from the exercise of stock options.
Question:
What are the company's primary source of liquidity from operations?
Answer: the collection of revenue in advance from our customers, accounts receivable from our customers, and the management of the timing of payments to our vendors and service providers.