Vesting is a tactic often used by startups alongside options in a company. A team member may be awarded a certain number of options at a specific valuation, but they do not own those options until a specific amount of time has passed. Often, these are done on what is called a "vesting schedule," where a percentage would be released at certain calendar dates. An example would be receiving 1,000 options in a company upon your start date, and then at 2 years you own 50% of the total (500 options), at 3 years you own an additional 25% (250 options), and at the conclusion of the 4th year, you will own the remaining 25%.