1)  Whole Life:  Fixed premium/fixed benefits.   Covers you for as long as you live if your premiums are paid. You generally pay the same amount in premiums for as long as you live.  when you first take out the policy, premiums can be several times higher than you would pay initially for the same amount of term insurance.  But they are smaller than the premiums you would eventually pay if you were to keep renewing a term policy until your later years. 

Some whole life policies let you pay premiums for a shorter period such as 20 years, or until age 65. Premiums for these polices are higher since the premium payments are made during a shorter period.  Whole life plans are the most expensive form of life insurance over the short term but can be the most cost effective over the long term because of the compounding of the cash value. 

2)  Universal Life:  Flexible premium/flexible benefits.  This is a kind of flexible policy that lets you vary your premium payments.  You can also adjust the face amount of your coverage.  Increases may require proof that you qualify for the new death benefit.  The premiums you pay (less expense charges) go into a policy account that earns interest.  Charges are deducted from the account.

 If your yearly premium payment plus the interest your accounts earns is less than the charges, your account value will be come lower.  If it keeps dropping, eventually your coverage will end. To prevent that you may need start making premium payments, or increase your premium payments, or lower your death benefits. Even if there is enough in  your account to pay the premiums, continuing to pay premiums yourself means that you build up more cash value in the side account.

Because of it's flexibility, Universal Life has become a vary popular form of life insurance.

3)  Term Life:  Fixed premium/fixed benefit.  Covers you for a term of one or more years.  Term insurance generally has lower premiums in  the early years, but it does not build up cash values that you can use in the future. 

Term policies are available for up to thirty years.  If your objective is to protect your family's financial future in the event you die prior to retirement, then term may be the right policy for you.

The National Association of Insurance offers significant free information and brochures to help you understand the different life insurance products:

http://www.naic.org/insprod/catalog_pub_consumer.htm