Most brokers use four or five levels. The lowest allows covered-calls and protective-puts; the next adds long options; then spreads; then cash-secured-puts; and the highest permits naked short calls.
Approval depends on stated experience, income, net worth and account size. It is worth understanding because a strategy you have researched may simply be unavailable, and because an approval downgrade can leave you able to close positions but not adjust them.
Example: you plan to roll a tested iron-condor by selling a new strangle at wider strikes. With spread-level approval only, the broker rejects the naked short call. You must close instead of adjust, realising the loss you were trying to manage.
Related: naked-call, naked-put, cash-secured-put, house-margin-requirement