Once learned, glyphs are permanent and may be switched out at any time outside of combat. Changing a glyph requires a [Vanishing Powder] for characters level 25-80, and a [Dust of Disappearance] for characters over level 80.
Major glyphs feature spell changes that may increase the damage, or another feature of the spell. Some of these glyphs have trade-offs. For example increasing direct damage but removing a DoT effect of the spell.
Minor glyphs
Minor glyphs give convenient or cosmetic improvements, such as reducing a spell's cost or removing the need for a spell's reagent.
This section concerns content exclusive to Cataclysm.
Initially, there would be additional glyphs known as "ancient glyphs", added with the Path of the Titans system. When Path of the Titans was cancelled, the glyph system was changed to three tiers - Major, Medium and Minor. This was later changed to the system implemented in Patch 4.0.1 - Prime, Major and Minor.[citation needed]
Notes
By default, the glyph UI is a tab on the talents window.
Players gain access to glyph slots based on their level:
Level 25: 1 Prime, 1 Major, 1 Minor.
Level 50: 2 Prime, 2 Major, 2 Minor.
Level 75: 3 Prime, 3 Major, 3 Minor.
Players who bought their Dual Talent Specialization will have two different sets of glyphs, and will need to activate a specialization in order to change its glyphs.
Glyphs can be installed at any time except when the player is in combat.
Like gems, once installed, a glyph is consumed. It cannot be recovered. Glyphs are no longer "used"; they are now learned.
Glyphs are now learned. Once purchased and read, they are added to a sortable library.
Glyphs are no longer destroyed; however in order to switch one for another you must use vanishing dust.
/Patch 4.0.1 (12-Oct-2010): Added Prime Glyphs and Glyph slots. The minimum level requirement to use glyphs is 25. You will unlock a Prime Glyph slot, a Major Glyph slot and a Minor Glyph slot at level 25, 50 and 75.