The tape of the theighs are usually worm by the Locks/Second Rowers #4 and 5 used as a grip to be lifted in the line outs. The tape in there head usually worn by front rowers #1 2 and 4 worn for protection against in scrums and rucks as the front rowers engage with collision and mainly to protect for cauliflower ears.

The tape above the knees is used by jumpers in the lineout. It gives the lifters a better grip. The tape around their head is simply a way to protect the ears, particularly during the scrum.

Tape on the head can protect an old cut. Head cuts bleed like crazy and are hard to stop. If its taped up there's less of a chance the ref will force you off the field. The tape is there for a grip for the guys lifting them on the line outs (on their head)

Head tape - To cover up bleeding, or to give the ears extra protection during scrum time, rucks and mauls as an alternative to a scrum cap. Knee tape - Simply to give the lifters a better grip when lifting them during the line out.

The tape above the knees are for the lineout jumpers. This makes it easier to grip for the lifters. The tape around the head are also usually for either hookers,locks, or loose forwards. This is to protect their ears. Because of all the friction caused in the scrums a lot of the forwards tend to get "colleyflower ears" where the blood builds up in the ear, and this is not the most attractive thing,haha

They are used for any sorts of injuries and cuts that bleed. Also personally it also helps sweatnot to fall in their face all the time. :)