The technique is ....
There are six M e t a p h o r i c a l hats and each hat represents a different style of thinking being used .So this putting on and taking off is essential ,, for it shows that you use "different ways of thinking instead of sticking to one way" only, and this is in fact the core goal of this technique.
In Details
White Hat
Headline: information
With this thinking hat, you focus on the available data. Look at the information you have, and see how you can benefit from it. And if your knowledge had gaps, you either fill them with information needed or just pay attention to them. Also the white hat analyzes the past experiences, and uses them positively.
For example, you say: I need more information before I decide or I did that before and my decision was wrong
Red Hat
Headline: Intuition
When you wear a red hat, you look at the decision away from logical thinking, using intuition, people's reaction, and emotion. Also you display your views without explanations or justifications, and you try to think how the others will react emotionally ,so you accept and understand their intuitive reactions.
For example you say: I don’t know but I feel that I'll fail 
or I'm afraid of doing this or I hate this plan
Yellow Hat
Headline: optimism
The yellow hat helps you to think positively . It is the optimistic viewpoint that helps you to see all the benefits of the decision and the value in it, and spot the opportunities that arise from it. Yellow Hat thinking helps you to keep going when everything looks gloomy and difficult.
For example you say: I'll succeed because I'll work harder next time and my success will lead to promotion
Black Hat
Headline: judgment
They call it also the "devil advocate" when using black hat thinking, look at things pessimistically, defensively and cautiously. Try to see the weak points in any idea or approach and try to find why they might not work. In fact, black hat thinking helps to make your ideas tougher and more flexible. Thus' it spots fatal flaws in your plans before you get on a course of action.
Actually, Black Hat thinking is one of the real benefits of this technique as many successful people get so used to thinking positively that often they cannot see problems in advance, leaving them under-prepared for difficulties
For example you say: I'll not pass this year because I'm not working hard or this project will fail because there's no enough money to continue
Green Hat
Headline: creativity
The green hat represents creativity . This is where you can develop creative solutions for our problems. Offering ideas and possibilities without much criticism, and here you can also use tools of creative thinking
For example you say: ok sense there's no enough money for this project why don’t we advertise for it and allow for new
partners to support
Blue Hat
Headline: thinking
The blue hat stands for process control . I mean control your thinking and which way or hat you should wear in a certain situation. For example, when you face a problem and you run out of ideas you know that a green hat is needed, or when you want to know if your current plan will work you will know that a black hat is needed and so on. Thus, it's mostly used by chair meetings.