Shifting security left means moving security checks as early as possible in the software development lifecycle — into the developer's IDE, into pull request checks, and into CI pipelines — rather than saving them for a final audit before release. The goal is to find and fix vulnerabilities when they are cheapest to address: during development, before they become embedded in production systems and customer data.
Analogy🏏Cricket
🏏 Think of it like cricket: A batting coach who only reviews a batter's technique after a tournament has already ended. The batter has played 10 matches with a flawed grip — every run scored with bad technique is harder to unlearn than if the coach had corrected it in the first net session. Shifting security left is bringing the coach into the net sessions, not the post-tournament review.