Just like in real life, practice makes perfect and in the World of Warcraft a character that repeatedly uses a particular skill will become steadily more proficient with it and thus be able to use it more effectively, in whatever way that applies. As the player levels up and progresses with a particular skill, they will reach certain minimum thresholds which are known as professional skill levels. The reason these are so significant is because the player will not be able to access new and additional skills and abilities until they unlock each specific tier of the skill ladder.
Broadly speaking, professions with the World of Warcraft game can be divided into two groups, primary and secondary, and whilst the player is restricted to an absolute maximum of two primary professions, they can have an unlimited number of secondary professions as well. Don't worry if you have taken a particular profession and do not feel comfortable continuing with it, as you can at your leisure remove that particular profession in order to clear space for a new skill. The only problem with this approach however is that you will lose all of the progress you have made with that particular skill so be careful about doing this. Note that the ability to drop a profession applies only specifically to the primary professions, and this is an option that cannot be used in relation to the secondary professions.
Professions can be grouped into one of the following classes:
The gathering professions are used to collect items from the various resources which are distributed across the world, in order to supply those ingredients to the crafting professions which will manufacture equipment and spells with them. The materials so collected can then be traded in a variety of different ways.
The production professions are responsible for producing new items from raw materials and it should be noted that whilst some items can be used straight away other items will require additional resources in order to make them actually useful.