What is the 3 year vesting requirement?

Excuse me, could you please clarify what exactly is meant by the "3 year vesting requirement" in the context of cryptocurrency or finance? Is it a condition attached to certain investments, tokens, or employment contracts where benefits or assets become available to the recipient over a period of three years? How does this mechanism work and what are the implications for those involved? I'm particularly interested in understanding its purpose and how it differs from other vesting schedules.