As it relates to testing, the phrase "80% coverage" means 80% of the

The phrase "80% coverage" in testing typically refers to the percentage of statements in the program that have been executed at least once during testing. This is known as statement coverage or code coverage. It is a measure of how much of the code has been exercised by the test suite and is used to assess the thoroughness of the testing efforts. It does not necessarily mean that 80% of the software is error-free, that 80% of planned test cases have been completed, or that 80% of predicted errors have been uncovered, although higher coverage often correlates with better defect detection.References:

Kaner, Cem, Jack Falk, and Hung Quoc Nguyen. "Testing Computer Software." 2nd Edition, Wiley, 1999.

Myers, Glenford J., Tom Badgett, and Corey Sandler. "The Art of Software Testing." 3rd Edition, Wiley, 2011.