The Update that Changed the World

The Update that Changed the World is a major update labeled as 1.7.2 released on October 25, 2013. It added many new features such as a new terrain generator, many new biomes and biome variations, stained glass, red sand, new tree types, new spawn system, new fish and fishing system with rewards, many new flowers, much more customizable options, Nether portals customizable up to 23x23, command blocks in minecarts and new commands.

Development began in one month after 1.6.2 was released. Fourteen development snapshots were released, from to. Several iterations of the launcher have been released during this time period, from 1.2.3 to 1.2.8. Nearer the end of the snapshot cycle for the 1.7.2 update, Mojang focused primarily on fixing bugs, rather than adding new features.

The official name for the update - the Update that Changed the World - was only announced three days prior to the 1.7.2 release on the Minecraft update tumblr (which is viewed in the launcher).

Mojang released the 1.7 pre-release on October 22, 2013 and the 1.7.1 pre-release on October 23.

Notable features
Notable Additions: Mesa, Mega Taiga, Roofed Forest, Birch Forest, Savanna, Extreme Hills+, Deep Ocean and snowless Taiga  See Biomes Acacia (Savanna Biome) and Dark Oak (Roofed Forest biome) trees, wood, planks, slabs and stairs  See trees Salmon, Clownfish, and Pufferfish  See fish
 * 11 new biomes
 * 20 new technical biomes
 * AMPLIFIED world type
 * 7 new commands
 * New particle effects
 * 6 new achievements
 * 4 new statistics
 * 2 new tree types, wood, planks, slabs and stairs
 * 3 new fish:

Roses removed and replaced with poppy  Blue Orchard, Allium, Azure Bluet, Tulips, Oxeye Daisy, Sunflower, Lilac, Rose Bush, and Peony.  See flowers
 * 10 new flowers added as decoration and/or easier-retrievable dye ingredients

Pufferfish -> Awkward Potion  See fish or Brewing Made using a square of 8 glass around a single dye in the middle  See Stained Glass
 * Potion of Water Breathing
 * Stained Glass and Stained Glass Panes (Only available in the current dye colours)

Notable Changes:
 * Improvements to existing biomes
 * Ocean biomes are smaller and take up less of the world
 * Treasures can be caught by fishing
 * Achievements and statistics are now per world/server
 * Fog is less noticeable on lower render distances
 * Re-added pre-1.6.1 boat controls
 * Weighted pressure plates are no longer limited to items
 * Unbreaking from enchantment tables is no longer limited to tools
 * Witches now spawn outside of Witch Huts
 * Render Distance and Max Framerate are now sliders
 * Cave Generation was tweaked, making caves less dense and interconnected.