An important reason people buy life insurance is to replace income that would be lost with the death of a wage earner. The cash provided by life insurance helps pay for final illness expense, burial costs, estate taxes, living and moving expense for the survivor.
Permanent life insurance provides cash value savings, available for emergency borrowing.  Permanent insurance provides lifelong protection. and is sold as Whole life, Universal Life, and Variable Universal Life.
Term insurance provides protection for a specified period of time.
One rule of thumb used is buy life insurance that is equal to five to seven times annual gross income.