I am used to enter, but I am not used to exit. You can find me in movie theaters and concerts.

On digits I'm all different, but come in three styles. I'm in every scripture, novel, each and all files. Blue ones of me are designers' magnum opus. To a specific machine, I am their focus.

In a hero's hands, I'm the means by which a great dragon they could slay. But move my first to my tail, and a still mightier weapon you'll find, some say.

I can be bitter or smooth, black or tan, expensive or cheap, fancy or plain

One strand dangles. Two strands twist. Three or more can fashion this.