Originally Posted by Knitette

Don't think you're ignorant at all - there's probably a few people who've read this and don't know either, but weren't brave enough to ask!

A straight stitch plate has a small round hole, just a bit bigger than the needle, whereas the generic or ordinary plates that normally come with modern machines, have a longish oval/kidney-shaped hole.

The long oval hole allows you to use the 'fancy' stitches such as zig-zag and blanket, which weren't usual on the older, traditional 'straight-stitch' models. Most modern machines now come with this bigger hole so the machines can use a variety of stitches - the needle 'swings' back and forth to make the stitch.

One of the disadvantages that this bigger hole has, is that it leaves plenty of room for fabric to 'disappear' into (something I am well acquainted with, particularly at corners). You may hear people commenting that their machine 'eats' their fabric and use small pieces of fabric at the beginning and end of sewing to prevent this (leaders and enders).

Some machines have a bigger appetite than others, lol. By using a straight-stitch plate, with a small hole, it prevents the fabric going into the hole and the need for leaders.