A Salesforce Tester is responsible for ensuring the quality and functionality of Salesforce applications by performing various types of testing, such as functional, regression, integration, and user acceptance testing. They create test plans, write test cases, execute tests, and identify defects to ensure the system meets business requirements. Salesforce Testers work closely with developers, business analysts, and administrators to validate configurations, customizations, and integrations within the Salesforce ecosystem. Their role is crucial in maintaining the stability and performance of Salesforce implementations.