1. What is static variable

a static variable is a class-level variable that is used to share the data among all instances of a class. It belongs to the class, not to any single object.

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

No object needed to access it

Access with class name

2. Difference between static and non-static variable

Features	Static variable	Non static variable
Belongs To	Class itself	Each object (instance)
Memory Allocation	Only once, for the class	Every time a new object is created
Accessed With	ClassName::$var or self::$var	$this->var
Shared Between Objects	Yes	No
Needs Object to Access	No	Yes

3. When to Use Static Variables

All objects of a class needs to share a single copy of data

4. When not to use static variable

each object of a class needs to store its own data

Can we use static variable instead of non-static variables?

Technically yes, But you should not use static variable if you want to keep separate copy of value for each objects

Can we use non-static variable instead of static variables?

Technically yes, But objects can not share the data. Every object will get its own copy