Many employers now offer 401k programs for their employees. The idea is that the employees will work with their employers to help them prepare for retirement in the future. Normally the company will offer to match up to a certain percentage of funds placed into the 401k by the employee.
The 401k is the investment vehicle used by corporations which gives employees a number of mutual funds to choose from to invest in. Many 401k plans also allow the employees to invest their money directly into the stock of their employer (if it is a public company) so that their money can grow along with the company. This is all great, but people change jobs often, so what are they to do with their 401k money when they do.
If you are changing from one job to the next, then you are going to want to use a 401k rollover in order to make sure that you retain all of the money you have put into it. Remember, your 401k is your retirement money, so you do not want to lose any portion of it.
You may not be able to receive the portion of the money that your previous employer had put into the account if you were not with that employer long enough, but you should be able to get all your money out. You will also get the benefit of any gains that you have made on your investment. You need to check with your new employer to make sure that everything will roll over into their 401k offerings. There may be some slight differences in the offerings, but they should be generally comparable.
Your 401k is one of the most important things in your financial life, and letting it rot away with your previous employer is a decision that you never want to make. Check this post on 401k rollover to IRA and solo 401k plan for additional information.