Term insurance is dramatically cheaper than permanent life — often a tenth of the cost for the same coverage — because most policies expire without paying out. It is the most efficient way to cover temporary obligations: a mortgage, children's college years, the working career of a primary earner.
Most policies are level term (constant premium and benefit). Renewable term lets you renew without a new medical exam, at much higher rates. Convertible term lets you upgrade to permanent insurance later — useful as health changes.
A 30-year-old non-smoker pays CHF 20/month for CHF 500,000 of 20-year level term life insurance — the cheapest way to protect a young family against income loss.