Different types of software testing include installation testing, usability testing, regression testing, performance testing, and security testing. Installation testing checks that a system is correctly installed and functions properly on a variety of hardware configurations. Usability testing observes users interacting with a product to evaluate ease of use. Regression testing re-executes tests on software that has undergone changes to ensure no new bugs were introduced. Performance testing evaluates how fast a system performs under varying workloads through load and stress testing. Security testing verifies that a system protects against unauthorized access and vulnerabilities.