The statutes that set the floor
Several California laws protect tenants' living conditions, led by the implied warranty of habitability and California Civil Code Sections 1941 and 1941.1, which set the landlord's duty to keep rentals livable and list the conditions that make a home unfit to live in.
A few others work alongside them. Civil Code Section 1942 describes a tenant's "repair and deduct" option in certain situations. Section 1942.4 limits a landlord's ability to collect rent when a housing agency has cited specific dangerous conditions and they go unfixed. Section 1942.5 protects tenants from retaliation — punishment for reporting problems or asserting their rights. Local building and health codes add more protection, and many cities have their own tenant ordinances on top of state law.
Together, these laws set a floor that landlords are not allowed to drop below. You do not need to memorize the code sections to be protected by them. If you think your living conditions fall short of what the law requires, a free review can help you understand which protections apply.
This is general information about California tenant rights, not legal advice. Every situation is different.