Skewer vs Fork vs Pin.

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AbikiAndHannah

So basically hi guys I am HimiandGeorge, gonna change my username soon, and these three are some of the best tactics in chess, but I wonder which one is more useful and powerful, and gains you more material? 

Fork: Queen-king fork using knight

Pin: Pinning queen to king using bishop

Skewer: Done with straight-line pieces, skweres king to queen. 

Which one is better?

AbikiAndHannah

What are ur ideas?

AbikiAndHannah

I need your opinions!