Life Insurance comes in many different forms but can be empirically boiled down to two types: Term and Permanent Life Insurance.
Term life insurance provides a level premium for a fixed period of time with a level death benefit (doesn't go down or up). The available term lengths commonly go from 10 years to 30 years and usually are in 5 year intervals (10, 15, 20, etc).
Permanent life insurance offers a longer length of coverage to a specific age, up to age 120, and can be a level death benefit or an increasing death benefit. Permanent coverage can be found in two different forms: whole life and universal life. In all forms premium can be variable, and can be pre-paid so a policy can perpetuate itself with no more premiums.
Term insurance can be the most affordable and is useful in covering short term needs such as: mortgage costs, lost income, future education needs for children.