Code is clean if it can be understood easily – by everyone on the team. With understandability comes readability, changeability, extensibility and maintainability. Clean code can be read and enhanced by a developer other than its original author. Please note "working code" is not the same as "clean code"! "Clean Code" by Robert C. Martin is a highly regarded book in the software development community, offering valuable insights and principles for writing maintainable, readable, and efficient code. If reading is not your cup of tea, below Udemy courses can be followed: 1) Learn to Write Clean Code with Java : Learn to Write Clean Code with Java. You can get Hands-on with Code Examples involving 4 principles of Simple Design, Refactoring & TDD. 2) Clean Code : This course is a compilation of common patterns, best practices, principles and rules related to writing clean code. Basic programming knowledge (no matter which language) is required!