Why? Because, if you become injured or ill (disabled), the life insurance company will pay your premiums so you can continue your life insurance coverage.
However, there is usually a waiting period for the premiums to be paid (6 months), but after the waiting period you are reimbursed for the premiums you paid during this time while you were disabled.
Learn more about how a life insurance waiver of premium works and why it may be a good idea to add this coverage to your life insurance policy, especially if you have a high risk job or take part in risky activities or hobbies.