What is the difference between log4j, slf4j and logback?

This link : https://medium.com/@krishankantsinghal/logback-slf4j-log4j2-understanding-them-and-learn-how-to-use-d33deedd0c46

Explains the differences in detail.

Quoting from there

Slf4j

So Basically Simple Logging Facade for Java serves as a simple facade or abstraction for various logging frameworks allowing the end user to plug in the desired logging framework at deployment time.

log4j2

Log4j,Logback and java.util.Logger are logging libraries which actually write the logs and have their own pros and cons. As industry standards are Log4j2 and logback

I would recommend going through the blog. It provides all the glory details how both are used with adapter.

Check out their home pages:

SLF4J - The Simple Logging Facade for Java (SLF4J) serves as a simple facade or abstraction¹ for various logging frameworks (e.g. java.util.logging, logback, log4j) allowing the end user to plug in the desired logging framework at deployment time.

^{1) It is not itself a logging library, but a generic interface to one of many logging libraries.}

Log4j 1.2 - Welcome to Apache log4j, a logging library for Java.

Logback - Logback is intended as a successor to the popular log4j project, picking up where log4j leaves off.

Log4j 2 - Apache Log4j 2 is an upgrade to Log4j that provides significant improvements over its predecessor, Log4j 1.x, and provides many of the improvements available in Logback while fixing some inherent problems in Logback's architecture.

At least, that's what they all say of themselves.