World of Warcraft Reputation (Renown) - let's start at the very beginning

Renown / Reputation is a measure of the favour you hold with a specific faction.

The levels for reputation (legacy renown from old expansions) are:

Neutral
Friendly
Honored
Revered
Exalted

To gain renown, you can complete quests in the area, kill big mobs (rares) or perform other tasks. Follow this blog for more details. 

To check your renown levels, click the letter U.

This opens up an interface showing all your renown for that toon.

Be aware, not all of the old renown is warbound, so if you want max renown on two toons, both have to do this grind. For example, you may want to buy patterns from more than one vendor, for alts' professions. 

I have learnt tailoring and leatherworking on one toon, which is working on max renown in all areas. If I want to learn any other profession from the old expansions, I will have to go through the process again.

Blizzard are working on making all renown warbound, one expansion at a time. Yay! It can't happen soon enough.

In the meantime, I've made a deal with some friends to do swaps, once we start making things for houses. I'll make all their tailoring and leatherworking furnishings, and will receive all the other goodies in exchange.