Why Quality assurance of software is important at its early stage?

Projects that don't set up processes to eliminate defects in early stages fall into extended test-debug-re-implement test cycles that seem interminable. So many defects are reported by testing that by the end of the project, the "change control board" or "feature team" may be meeting as often as every day to prioritize defect corrections. Because of the vast number of defects, the software has to be released with many known (albeit low priority) defects. In the worst case, the software might never reach a level of quality high enough for it to be released. That’s why software testing is important from day one.

Quality should not be targeted through corrective actions at the project end ….. as this can be very costly and time taking. Instead the quality should be built in as much as possible by preventing defects to occur. Quality assurance and software testing in early stages of project helps in taking such preventive measures in timely manner.