Vesting is the process of scheduled issuing of shares or share options for employees for an agreed period of time. This is to ensure that the employee is rewarded for the contribution they bring to the company. A concept to bring up is a 'cliff'. This is a period in which shares and options vest, but are not issued until the completion of the period. This is typically a year (sometimes more - a warning sign if significantly more). This means that after a certain number of shares have been issued after the cliff (e.g. 25%), the remaining shares are issues periodically over the remaining period (Typically 4 year).