Ruby has three kinds of variables, one kind of constant and exactly two pseudo-variables. The variables and the constants have no type. While untyped variables have some drawbacks, they have many more advantages and fit well with ruby's quick and easy philosophy.
Variables must be declared in most languages in order to specify their type, modifiability (i.e., whether they are constants), and scope; since type is not an issue, and the rest is evident from the variable name as you are about to see, we do not need variable declarations in ruby.
The first character of an identifier categorizes it at a glance:
The only exceptions to the above are ruby's pseudo-variables:
You man not assign values to