Vesting Cliff
The initial period (usually one year) during which no equity vests at all.
Definition
The cliff is a waiting period at the start of a vesting schedule during which no shares vest. The standard cliff is one year. If you leave before the cliff, you receive zero equity. Once you pass the cliff, a large chunk vests at once (usually 25% of your total grant), and then shares vest incrementally going forward. The cliff protects the company from granting equity to employees who leave quickly.
Why it matters
If you are approaching your cliff date, it is worth waiting to pass it before leaving. Missing your cliff by even one day means you lose 25% of your grant. Some offers include shorter cliffs (6 months) as a negotiation point.
Example
You join on January 1 with 40,000 options and a 1-year cliff. If you quit on December 30, you get zero options. If you wait until January 1 of the next year, 10,000 options vest immediately.