declare a boolean in Ruby

bool_var = true

In the above code, a boolean variable is declared in Ruby by assigning the value “true” to the variable “bool_var”. A boolean variable stores true or false values and can be used to create conditions in a program. For example, if bool_var is equal to true, then a certain section of code runs, or if it is false, then a different section of code will run. This type of conditional programming is very common and is used to create flexible programs. The value of boolean variables can be changed which can create different outcomes for the program. In this way, boolean variables are used to store states in a program.