Relational operators are those used for comparisons and are all binary operators: less than (<), less than or equal to (<=), greater than (>), greater than or equal to (>=), equal (==) and not equal (! =). Discussion of what exactly equals means is deferred for the minute, but it's safe to say if the two things compared are of the same type, then equal means 'the same as' in the commonsense way you'd expect.
a < b; a >= b; a == b; (a + b) <= (c + d);