The tension adjuster on your sewing machine is one of those mysterious dials that many sewists try to avoid touching. If you’re having a problem, you’ll often hear “It’s probably a problem with your tension settings” but not much else on how to actually fix the problem.
Thread tension itself isn’t a very complicated idea, but adjusting and perfecting it can be a little intimidating since you have top thread tension and bobbin thread tension which are adjusted completely separately.
While browsing Pinterest (side note: SMYS now has a Pinterest!) I came across a link to this blog post by Threads Magazine that thoroughly explains thread tension and is well worth a read.
If you feel that this is a bit advanced for you at this point, definitely hold onto it for later reading if you’re having trouble with your sewing!