image from Janome website
Where would I be without my walking foot? Most likely spitting out a lot more expletives when sewing than I do now.
What does it do? Well, this little metal magician has feet that grab onto the top of your fabric and feed it through in conjunction with the machines feed dogs, which are the little teeth under your presser foot. In doing this it prevents the fabric from shifting and therefore causing it to pucker.
For example, when you are sewing two pieces of fabric together and you've pinned them nicely and they fit perfectly, but when you finish sewing them one edge is longer than the other or there is a bubble in the fabric edge. Well, this baby will prevent that from happening and hence make you a much happier sewer.
This is the foot that you would use to sew PVC and leather. It's also great for slippery fabrics or when you're sewing fabrics where you need to match up the stripes or checks on each side.
Here is a link that gives a little demo on the walking foot.
I use my walking foot ALL the time, it's not cheap, about $100-$150 depending on your machine but well worth the investment in your sewing and keeping your mouth clean, as a lady should after all.
p.s A lot of stores will be having Mothers Day sales, so it's a good time to check out the price.