Time To Interactive (TTI) is a web performance metric that measures the time from when a page starts loading to when it becomes fully interactive for the user. A lower TTI indicates that users can engage with the page more quickly, enhancing their experience.

Factors affecting TTI include JavaScript execution, rendering processes, and resource loading. Optimizing TTI involves minimizing render-blocking resources, deferring non-critical scripts, and optimizing code execution to ensure that the page responds promptly to user inputs.