Vesting
A rule that releases an allocation of tokens gradually over time instead of all at once, usually for founders, staff, and early investors.
A vesting arrangement has two parts. The cliff is an initial period during which nothing is released; if the recipient leaves before it, the allocation is normally forfeited, and when it passes a first tranche unlocks at once. After the cliff, the remainder releases linearly, typically per block or per month, over a further period measured in years. The purpose is to tie the people who received supply cheaply to the long-term work rather than to the launch. Enforcement varies and matters: a schedule executed by an on-chain vesting contract can be verified by anyone, whereas a schedule described only in a document depends on the parties honoring it.
In practice
A one-year cliff followed by three years of monthly vesting means nothing is released for twelve months, after which roughly one thirty-sixth of the remaining allocation unlocks each month.
The common misunderstanding
Locked does not mean inert: locked allocations can still be borrowed against or sold forward through private agreements before a single token has unlocked.