What are Exploits? How important are Exploits for Hacking ?

Ref- itpro.co.uk

A tool developed by hackers that is used to perform malicious attacks on computer systems. They are usually scripts that are designed to exploit weaknesses in software over a network, most commonly the Internet.
        "Zero-Day" is a common type of exploit.You can hack in many different ways with many different procedures. Kevin Mitnick created hacking history with just a phone and a dream. Hackers, Exploit writers and Defacers are always the challenge for Security Experts and Compa-
nies.An attacker can write exploits because of some misconfiguration, unsecure development and is lacking IT management.
                 
There are various Exploit Database sites available with thousands of Exploits.

For example: