Stitch markers are a topic knitters have very different views on.
Some swear by them and use them in every project.
Some have never tried them and frankly can't see why they should bother in the future, either.
And then there are people like me, who love them but realise they are not essential for each and every knitting project.
There are some types of projects and situations that do benefit from using stitch markers, though.
Here is one of the knitting situations I wouldn't dream of working on without one or more of my little helpers: the sweater! My number one project I couldn't think of finishing without stitch markers is a sweater knit in the round - either top-down or bottom up.
For example the bottom-up sweater.
You cast on, join the round and start working.
After an inch or so you have to start checking again and again where exactly the start of the round is, as the possible yarn end left over from the cast-on won't give you information without looking very closely.
It's much easier to use a stitch marker! And that's just the start! If you are planning on working some waist shaping into the sweater, you will be needing at least two if not four stitch markers more: two if you are planning on making your decreases and increases right around the side stitches, four will be beneficial if you want to make your shaping a few stitches apart from the side seam (this is more flattering on many body types).
If you are starting your sweater from the top, especially when working a raglan sweater, stitch markers are irreplaceable.
How else would you know when exactly you should be decreasing for the sleeves? The little helpers will save you from a lot of counting!