Being a newb at this hobby, I have a lot to learn. One of the first things I need to know is how to differentiate sizes and quality in paracord I'm considering purchasing. I read the wiki on parachute cord at https://en.wikipedia.org/wiki/Parachute. I couldn't relate the wiki to the information I see on most websites selling the stuff. Probably the most common size in 550, but I think that not all 550 is equal. I read about 'mil-spec' when reading about some 550 but not others. Next, I see 440 fairly commonly on offer. TIAT uses this size a great deal in his YouTube videos. Having knotted a few bracelets, monkey fists, and handle wrappings, it seems that 440 might be a more suitable size for some things but not others. What makes 440 different from 550? Fewer internal strands? If so, how many strands should there be in each? Then, I see some cord offered as 275. What is this? What uses does it have? When should I consider 275 as opposed to other sizes? Finally, I'll ask about the use of the terms 'micro' and 'nano' to describe cord. I really haven't seen this much - mostly from one online seller - and would like to know what these terms mean, especially in relation to 550 and 440 sizes. BTW: I think this would make a good subject for an expert to write up and post here as a sticky or in FAQ (which I haven't found on this forum). Cheers!