Manifest V3 is the latest specification for Chrome extension development introduced by Google. It replaces Manifest V2 to improve privacy, security, and performance. Manifest V3 restricts certain extension capabilities, such as background pages and the use of powerful APIs, to reduce the risk of abuse. It introduces service workers for background tasks and limits network request modification, impacting ad blockers and similar tools. Developers must update their extensions to comply with these new rules, which are designed to give users more control over their data and enhance browser security. Manifest V3 is now required for all new Chrome extensions.