This document discusses software development best practices including unit testing, integration testing, continuous integration, and continuous delivery. Unit testing isolates and tests individual code units to verify they work as intended. Benefits include finding problems early and allowing refactoring without fear of regressions. Limitations are that tests only check for certain errors and require additional test code. Common unit testing tools include JUnit and Mock objects which simulate objects for testing. Integration testing combines modules tested individually. Continuous integration runs automated tests and builds on every code change. Continuous delivery fully automates the software delivery process.