A shift left testing approach involves moving testing activities "left" or relatively "early" in the development cycle. Thus, testers are involved earlier in the software development life cycle, enabling them to identify bugs and bottlenecks at an earlier stage. In addition to improving the quality of the code and reducing the time it takes to complete the cycle, it helps ensure fewer defects are introduced to production.
Organizations are constantly challenged to move faster in an agile environment. Typically, this entails shortening the delivery time while improving quality with each successive release at reduced costs.