SLF4J is a simple logging facade that allows switching between different logging frameworks at deployment time without code changes. It provides a common interface for logging and allows migrating from one logging framework like log4j to another like JDK logging easily by changing a jar file. Popular frameworks like Logback, Log4j, and JDK logging have SLF4J bindings. Using SLF4J avoids vendor lock-in and allows plugging in the desired logging framework.