Example :looking for the name 'John Smith' in the phone book
● Open up the phone book approximately half way
● Look at the name at the top of the page.
● Does Smith come before or after this in the phonebook?
● After, right? So you can ignore the entire first half of the phone book.
● Now open the remaining half about half way.
● You're probably somewhere near the 'T's.
● Does Smith come before or after 'T' in the phonebook?
● Before. So you can ignore the latter half.
● Continue doing this until you find the name for which you're looking.
Binary search involves binary decisions, decisions with two choices. At each
step in the process you can eliminate half of the data you're searching. This
is the way humans look up most information in big volumes, such as a
phonebook or a dictionary.