Steek stitches are extra stitches that allow you to knit in the round without having to worry about armholes for sweaters, fronts of cardigans, and when they're used for blankets it helps with distributing the weight, they are often used later as fringe. They're used a lot in Fair Isle knitting because you are always looking at the front of the pattern.
You knit the extra stitches as you make the item, and then cut them later. It sounds scary, but it really does make sweater knitting easier, and I imagine knitting a blanket in the round would be easier than flopping it back and forth as it got bigger.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog