What is a public key encryption system? 

The key and lock phenomenon is easy enough to understand. Only the person with the key can open the lock. Similarly, when an encrypted file is made, a special key is embedded in it that secures the file. Now, only the developer with the specific file is able to use decode the source and hence, only the correct receiver can decode the data.

This is an efficient means of protecting the files and contents and allows developers to send valuable info without the risk of theft. Moreover, certain programs are payed with a special key and this enables only valid users to use them.