[swaroop]

I want to know the functions of catalysts for better understanding of reactions.
Can anyone give a list of almost all catalysts and their functions..
I am currently studying in class 12.

[discodermolide]

This is an impossible task! There are 10's of thousands if not 100s of thousands of catalysts around or even more.
You do not specify an area of chemistry, inorganic, organic, biochemistry, industrial chemistry and so on.
So you will have to be more specific and ask about one particular catalyst that interests you, or one particular catalysed reaction. But please don't expect anyone to have such a list.

[Arkcon]

Furthermore, some of them are patented, or trade secrets.  You won't find such information out just by asking on an open forum.  This could take a lifetime of work by you.  Instead, you should just pick one example, and begin to learn the basics about it.

[swaroop]

I want to know the functions of catalysts for better understanding of reactions.
Can anyone give a list of important catalysts (and their functions) used in Organic Reactions related to general syllabus of class 11 and 12 .. I searched the internet but could not find it.
I am currently studying in class 12. 

[Arkcon]

I hope you don't mind, swaroop:, that I've merged this new post with this older one of yours.  It seems you wanted to add more information, but the responses you got the first time still apply, even with your slight change.

[Zensation]

swaroop,

Just about anything can behave as a catalyst. Whether or not something behaves as a catalyst, a reactant, or nothing at all, entirely depends on the reaction circumstances. With the right reaction circumstances, it wouldn't be too far off to say that everything compound can behave as a catalyst. A catalyst is nothing more than something that speeds up reaction conditions without being consumed.

[curiouscat]

I want to know the functions of catalysts for better understanding of reactions.
Can anyone give a list of important catalysts (and their functions) used in Organic Reactions related to general syllabus of class 11 and 12 .. I searched the internet but could not find it.
I am currently studying in class 12. 

I see several problems: You expect people to know what's the syllabus of whatever school system you go to? Why should someone waste his time typing out such a list for you when a few minutes on Wikipedia or Google would throw many many examples?