We have threaded the warp with the vertical threads (see Melacha #17) and set the heddles to raise and lower these threads in succession (see Melacha #18). Our loom is now ready to weave. Passing the woof threads perpendicularly over and under the warp threads is weaving, also known as the melacha of oreig.
One need not necessarily use a loom to weave. The basics of weaving are the same whether one is making a basket or a Medieval tapestry. Accordingly, making a lanyard or fixing a wicker chair on Shabbos might be a violation of oreig. Similarly, attempting to repair a snagged thread on a garment by pulling it back into shape is an issue of oreig.
Braiding a wig is also a form of weaving and therefore prohibited on Shabbos. Braiding the hair growing on one’s head is not considered weaving, but it is forbidden under the melacha of boneh (building, Melacha #34). This is comparable to way that combing a wig may present issues of menapeitz (combing) but combing one’s hair presents issues of gozeiz (shearing – refer back to Mitzvah #14 for more on this matter).
This is just an introduction to the concepts of the melacha of oreig; it is not a substitute for a full study of the halachos.