1. What is static function

a static function is a class-level function. It belongs to the class, not to any single object.

the keyword "static " is used to declare a static function

No object needed to access it

Access with class name

2. Difference between static and non-static function

Features	Static function	Non static function
Belongs To	Class itself	Each object (instance)
Accessed With	ClassName::method()	$object->method()
Access $this	No	Yes
Access static vars	Yes (self::$var)	Yes
Access instance vars	No	Yes ($this->var)
Object creation needed	No	Yes
Inheritance	not polymorphic	supports inheritance & overriding

3. When to Use Static function

It is used when the method does not access instance properties ($this->var) . Data is passed as function parameter

4. When not to use static function

It is not used when the method access instance properties ($this->var)

when you plan function overriding

Can we use static function instead of non-static function?

Technically yes, when If the Function Does Not Use Object Data.

Can we use non-static function instead of static function?

Technically yes, But It wastes memory. Each new object takes up extra memory

What is static class

Static class is a class which contains only static properties and static functions