How To encrypt disk partition with LUKS in 9 easy steps

Normally Linux servers are very much secured and illegal or unauthorised access is almost not possible with security policies in linux. However if linux can be installed on the laptop which makes it unsecured and worst situation occurs when you forget the laptop in public places such as trains, airports or bus where any proficient person can get access to your laptop. To bypass this situation we can encrypt disk partition with LUKS.