This four letter word can be found almost anywhere from something small like a watch to something huge like a wind turbine. It comes in a myriad of sizes. And performs many different functions depending on how and where it's used. It can also be used as a slang term for clothes, equipment, or more commonly for party pills. Another less common use for this word is a transitive verb. You might hear someone using synonyms like bracing themselves, or psyching themselves up. This word has sixteen definitions, I've given a few, now it's up to you.

I’m not a page, but I know where you’ve been, I wait between chapters, quiet and thin. I help you return when you’re ready to read, Without me, finding your place takes more speed. What am I?

If I am a circle, I can make sure you don't go in circles. If I am not a circle, I can make circles. What am I?

I guard what’s yours, then demand a tiny metal bribe.

I dance in the dark I’m gone, then I’m back I shine from a wick Who am I, so quick?