An expression in Ruby can be thought of as a line of code and the return value of every expression is an object. The IRB REPL (read-eval-print-loop) is an ideal environment for demonstrating that every Ruby expression evaluates to an object as the return value is printed after every statement. Here are some examples:
>> 5 == 5
>> x = "Bob"
>> puts "hi" if nil
>> 1 + 2
The return values in the example expressions return true, “Bob”, nil, and 3, all of which are objects.