Importance of Scanning in hacking

Scanning is an art of gathering information of the target computer.
Information like -IP address ,open port running on the target computer,services running on the computer and vunerability of operating system that is running on the target system .
Scanning can be divided on to three parts
1st network scanning.
2nd port scanning .
3rd vulnerability scanning.
Network scanning-In "network scanning" a hacker scan a network to check a live system in a network and it also check the ip address in which these system are live.
few tools that help to check a live system in a network
*angry ip (free tool that can be downloaded from google)
*ping sweep (free tool that can be downloaded from google )
Port scanning - In "port scanning " a hacker gather information of all the open and listening port that is running on the target computer .Few tool that help us to do a port scanning are
1)nmap
2)hping2
3)atelier web port traffic analyzer (AWPTA)
4)atelier web security port scanner (Awsps)
vulnerability scanning- In this scanning we check the loop holes in an operating system .
you can gather these info from website like www.nta-monitor.com ,http://tools.securitytube.net
*note- please donot try to run these tools on a live system it is a good practice that try to play with these tool on VM-ware.