I am installing android for the first time on my computer, but "Downloading Components" taking lots of time.
I want to test and run some very small apps. Can i do without those components.
Do i really need that at start.
Short Answer: Yes you need them!
(I am assuming that you have the sourcecode of an app and you want to build it with android studio. If thats not the case check the answer of Beppi's.)
You can read about this components in the following links. This will give you a understanding why you need to download them separately regarding to their version you use: