Selvedges? What exactly are they?

Hi there! I’m fairly new to this knitting business - in fact I only taught myself how to knit using a book a couple of months ago!
Now I’m hoping to make my first scarf…
Please forgive my ignorance but I’m hopelessly confused…
What exactly is a selvedge?
From what I’ve been reading is it an edge at the bottom or is it ont he sides of the knitting and when you finish do you end with one?
Are you supposed to cast on first, then begin your first row with a selvedge?
How does a selvedge get included in the number of stitches you cast on? For example I’d like to start on a scarf where the instructions tell me to use a “slip-stitch selvedge”. It tells me to cast on 40 sts and to work in k1,p1 rib. (Does that mean after the selvedge as described below I really on have 38 sts in the pattern and the first & last two sts are for the selvedge?
According to the book you slip the first stitch knitwise and knit the last stitch on the knit rows.
Is the knit row the first row after you cast on (so that is the right side?)
Please help…sorry about my many qs…


Selvedge comes from the words self edge. Your scarf has a selvedge built in to the pattern. Sometimes it’s not, but then pattern usually tells you to add 2 additional selvedge stitches. So you will have 38 ribbed stitches between the two selvedge stitches.

The purpose of having the slip-stitch edge on your scarf is to give it a nicer edge than you would get if you just knit the end stitches one very row.

When I work selvedge stitches on a scarf, I usually slip the first stitch as if to purl and knit the last stitch of every row. You don’t HAVE to do it this way, but on a ribbed scarf you don’t really have a knit row or purl row. In fact, I’ve never heard a pattern say to do the selvedge stitches differently on knit or purl rows.

Thanks Ingrid! I never knew that and you’d think I would consider I’m also a quilter and know all about fabric selvedge!