What are the differences between Constant and Variables in swift

A lot of people can't figure out how to declare variable and constant in swift so today this tutorial i want to writing about constant and variable Only the first part of the statement is different: You declare constants using let, whereas you declare variables using var
you can use almost any character you like for constant and variable names including Unicode characters:

number = 4

let 🐶🐮 = "dog cow"

Constant and variable names cannot contain   mathematical symbols arrows private-use(or invalid) unicode code points or line and box-drawing character nor can they begin with a number ,although number may be included elsewhere within the nameonce you have declared a constant or variable of a certain type ,you contain type ,you can't redeclare it again with the same name or change it to store values of a different type.Nor can you change a constant into a variable or  a variable into constant

you can change the value of an existing variable to another value of compatible type in this example ,the value of "variableNumber" is changed from " variableNumber"

var variableNumber:Int = 3

variableNumber = 4

unlike variable the value of a constant can't t be changed one it is set .trying  to do so is reported as an error when you code compile

Cannot assign to value: number is a let constant Constants are useful for values that aren’t going to change

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