Use the assignment operator (:=) to set or change the value of a [local variable](/microbit/reference/variables/var) or a [global variable](/microbit/js/data).
### Declare a variable
Declare a new *local* variable using the [var](/microbit/reference/variables/var) statement and the assignment operator (`:=`). Like this:
```blocks
let num1 = 7
let name = "Joe"
```
The variable's name is on the left of the assignment operator (`:=`) and the variable's value is on the right:
*variable name* `:=`*value*
See [global variable](/microbit/js/data) for info on declaring a global variable.
### Change a variable
After a global or local variable is defined, use the assignment operator (`:=`) to change the variable's value.
```
g = 42
num1 = 42
```
### Notes
* Don't confuse the assignment operator `:=` with the equality operator `=`, which is used to compare values.
* You can use the assignment operator `:=` with variables of each of the supported [types](/microbit/js/types).
