"do not join"

First post! Hi all :slight_smile:
I am a FAIRLY new knitter, haven’t done anything with a pattern yet, not really anyway, and I have taken on a baby blanket for a friend. I have a fairly simple question…
The pattern says " Cast on 181 Stitches. Do Not Join. Working back and forth across needle, proceed as follows: 5 rows garter st, noting that first row is WS.“
What is “do not join”?? and " working back and forth across needle?” Is this any different from just knitting on as one normally would? I’m also guessing that my cast on does not count as my first row.
Any guidance with this would be greatly appreciated.

Usually when you knit with circular needles, you join the stitches so you can work in a circle and end up with a long tube, like the bottom of a sweater.

Because of the number of stitches on a blanket, you use a circular needle just for the length needed to accommodate the stitches

Just work back and forth on the needle as you would with straights, as if each point was a separate needle.

Cast on is just cast on. It’s not the first row.

Thank you so much! I figured it was probably as simple as that, but I wanted to make sure that I wasn’t venturing into some weird knitting lingo that I hadn’t come across yet.
I’ll probably be back with more :lol: Thanks again!