Data Type Variable , Variable; Only declare a variables when you need them.
Variable Names have some best practices. Variable Naming Conventions
Variables must be Declared Variables must have an assignment of value, to be used in the code. Variables can also be initialized by declaring it’s Data Type and then assigning it the required value.
Sometimes, there is no need to assign it to a data type. This happens when you use var data type to declare the variable. This is called Implicit Declaration of Variable