number that does not change
letter that represents some number
contains at least on evariable
expression that is a number, variable, or product of one or more variables
a monomial or sum/difference of monomials
have the EXACT SAME variable parts
order of operations
any number tha can be found on a numeber line
can be represented as a quotient of 2 integers or can be written as a terminating or repeating decimal
0, +1, +2, +3,...
0, 1, 2, 3,...
1, 2, 3,...
any numbers tha aren't real