All characters in "World of Warcraft" can pick up Dual Talent Specialization, a feature that enables them to use two interchangeable specializations. For hybrid or multi-role characters like the Druid or Paladin, this enables you to fill more roles as needed by your guild or party like tanking or healing in addition to DPS. For DPS-only roles, it gives you the chance to experience the different play styles of your class: for example, a Mage could try out both the Fire and Arcane play styles, instead of choosing just one.
Obtaining Dual Talent Specialization
Any character, regarless of class or faction, can obtain Dual Talent Specialization at level 30. Find your class trainer in any major city and speak to them; the option is available along with resetting glyphs and talents. Dual Talent specialization isn't free: it costs 10 gold to purchase. However, unlike resetting glyphs and talents, which increase in price the more times you do it, dual spec is a one-time cost.
Setting Up Your Second Spec
Your second specialization doesn't come ready-made: you have to set up everything about it. Once purchased, select and activate the second spec in the talents window. Choose your new specialization and any talents you have available, then start equipping your glyphs. You also have to set up your action bars with your new spells and configure any add-ons you use appropriately.
To switch specs, open the talents window with the "N" key, select the inactive specialization from the two buttons on the side of the window and click "Activate." Being able to change roles on the fly is handy, especially if a tank or healer quits in the middle of the raid. However, in many cases you do have to carry twos set of gear with you to ensure optimal performance in either role, which uses valuable inventory space.