Rugby shorts worn by players in a few of the top clubs will carry the club name and in some instances the sponsors name. The majority of shorts however are just plain with the most common colours being dark blue or black. The latest offerings include modern synthetics but with consideration of the contact with the face and the need to ensure no skin burns. This leads to the majority of shorts being cotton.
We are not sure how shorts have evolved but believe it started with players simply wearing their out door cloths with the bottoms tucked into their socks. This moved on to long johns the woollen undergarments being used or pantaloons the baggy trouser that was three-quarter length. The next progression was to shorts that came down to the knee. These were still common up to the 70's. We now have the shorts of today which are often warn with cycle shorts underneath.
The underwear in the modern game is usually briefs which give good support. However until the 70's the common gear for support was a jock strap which gave positive protection rather in the fashion of a box in cricket.