fn main() { // declare a variable // and assign value to it let x = 1; println!("x = {}", x); }let my_var : type = value; // by default no variables can be changed // you must define a variable as mutable if you want to change its value let mut var_name : type = value; let other_var = var_name; // you can ommit the type if it's easy to guess // const are variable that can never change, their values must // be known at compile time and their type must be explicit const THREE_HOURS_IN_SECONDS: u32 = 60 * 60 * 3;let <name>:<type> = <value> //keyword "let" can only be used inside a function