What's the right order and isolation period for introducing cats? (Essential for multi-cat households)

Quick answer

Since cats are territorial animals, introductions must go very slowly, step by step. Spend the first 3–5 days in complete separation with cats in different rooms out of sight of each other, then swap blankets or toys to get them used to each other's scent, then feed treats on either side of a safety gate or screen door for brief face-to-face contact, and finally allow short supervised direct meetings under strict owner control. If hissing is severe, go back a stage — rushing the process is the surest way to make them lifelong enemies.