Excerpt: Some companies have what's called 100% vesting, meaning that the employee immediately owns any contributions made by the company on his or her behalf. But other companies use 'graduated vesting,' typically turning over 20% of its contributions to the employee after one year, working up to 100% after five years, he says. Then there's 'cliff vesting,' where 'you don't own any of the contributions unless you've been there for, say, three years. Then, you own 100%.'  MORE >>