Code conventions
Programming in groups, and even alone, becomes harder without them. Without what? Without Coding conventions! Never heard about it? Then you probably aren’t a programmer!
What are they in short? How to write and choose a name for a class, a variable, a setter or getter, a button, and more. It could also be a rule, that says when you have a string variable, you name it strVariableName. CamelCase (upper and lower) are one of the important things in coding conventions, it’s about Uppercase letters.
When everybody uses the same conventions in a project, it’s easier to understand code other people made!