The five components: Principal and Interest (your loan payment), Property Tax (county tax, held in impound for most loans), Homeowners Insurance, and Association dues (HOA or condo dues if applicable).
Lenders use PITIA (not just PI) when calculating DTI for qualification and DSCR for investor loans. A low interest rate doesn't help if property tax and HOA push PITIA beyond your qualifying income.
California specific: high property tax ratios (typically 1.1–1.3% of purchase price) and often higher insurance premiums (post-wildfire) make PITIA calculations meaningfully different from lower-tax states.