The document discusses various software reliability tools and common software errors. It describes tools like SMERFS, SRMP, SoftRel, and CASRE which are used for statistical modeling and estimation of software reliability. SMERFS is designed to estimate and predict reliability during testing using failure data. SRMP contains nine models and uses maximum likelihood estimation. SoftRel simulates project occurrences using a Piecewise-Poisson Markov Process. CASRE was developed by NASA to make reliability estimation easier. Common software errors discussed include errors in handling, preventing, detecting and recovering from errors, as well as boundary, calculation, initial state, race condition and load condition errors.