The rights the law protects
California's retaliation law protects tenants who exercise a range of legal rights connected to their housing. The point is that using these rights should never expose you to punishment.
Protected activities generally include complaining to your landlord about the condition of your home or requesting needed repairs, reporting habitability or code problems to a government agency like a building or health inspector, using a legal remedy such as repair-and-deduct, and participating in or organizing a tenant association or group acting to improve conditions. Lawfully exercising other tenant rights can be protected too.
The common thread is that you are acting within your legal rights regarding your tenancy. When you do, the law aims to shield you from retaliatory rent increases, service cuts, evictions, and similar punishment.
Knowing your activity is protected matters, because it is often the foundation of a retaliation claim or defense. If you exercised one of these rights and your landlord responded with a negative action, a free, confidential review can help you understand whether that action was unlawful retaliation.
This is general information about California tenant rights, not legal advice. Every situation is different.