Rug Underlay
In many cases, Moroccan rugs will need an underlay pad, particularly older and more delicate rugs, and if a rug is to be laid on stone or wood floors And they will need a particular sort of underlay since rugs on hard floors demand cushioning to make them comfortable to walk on. As very few rugs will sit even with the floor, a pad also allows them to lay flat and look lovely. Rugs laid on hard floors can easily slip and move around, so they also need something to help them stay in place and to avoid them ending up being a tripping hazard.
Look for an excellent quality cushioned underlay: just less than half a centimeter thick should be right for a lower pile vintage rug or a kilim, although using a pad that is too thick can cause the rug to wrinkle. Buy an underlay that can be cut (or that you can cut) to fit the rug and opt for a size that is about 5 centimeters smaller all around to allow for the rug to slope down around the edges. Too big and it will cause the edges to ruck up, too small and it will not work properly.
FOXI underlay is great and lots of suppliers sell it online, and many will cut it to size for you.
Some people use double-sided sticky carpet tape as a grip on hard floors. This can be useful for awkward corners but be careful that it does not mark the wood or stone.
Suppliers of rug pads include: