Cryptography is a method of protecting information and communications through the use of codes, so that only those for whom the information is intended can read and process it. Imagine cryptography like you have a key, you can give the same copy of this key which opens a lock other people who do not have the same key can not open this lock, only the person you gave this key to can access and open this lock, anybody else that tries to open it with a different key will be denied. This is also called encrpytion.