Boolean enumeration is used to discover data when you can only ask the an information system yes or no questions about a value.
This is especially useful in SQL injection.
As we know because of hexadecimal, the largest value any byte can hold is 255. So, we can ask the question:
Is the value of our one byte at this position greater than 128?
If so, we can add 64 to 128 and ask if its greater than that. Otherwise, we can ask if its greater than 64.
Eventually you will have to use less than and equal to as questions. Once you get the value, you can move onto the next byte.
Guess a number algorithm
Let there be a number N we know to be between bounds A and B Our guess is G