The following description was taken from the NHS website:
Cognitive behavioural therapy (CBT) is a talking therapy that can help you manage your problems by changing the way you think and behave.
It is most commonly used to treat anxiety and depression, but can be useful for other mental and physical health problems.
CBT cannot remove your problems, but it can help you deal with them in a more positive way. It is based on the concept that your thoughts, feelings, physical sensations and actions are interconnected, and that negative thoughts and feelings can trap you in a vicious cycle.
CBT aims to help you crack this cycle by breaking down overwhelming problems into smaller parts and showing you how to change these negative patterns to improve the way you feel.
Unlike some other talking treatments, CBT deals with your current problems, rather than focusing on issues from your past. It looks for practical ways to improve your state of mind on a daily basis.