Hotkey

A hotkey is a key or set of keys which perform a specific function with regards to time efficiency. In StarCraft, hotkeys are vital as they allow for orders and commands to be delivered quickly, thus allowing for better control, management, and more time.

Universal
Note: You can also Ctrl-shift click units too, to get the combined effect of adding all units of that type visible on the screen to your current group.
 * F10 - Menu
 * Ctrl 0-9 Assigns hotkey to a specific group (ie if you select 12 marines and press ctrl 1, you can tell the twelve to attack by pressing 1, then attack.
 * Shift click Queues up moves: ie to get a worker to build then mine, hold down shift, click on the building you want to build, then click on where you want it to go, then click on the mineral field. let go of shift. Another use of shift click is to remove or add units to the currently selected group.  By shift clicking a portrait or the unit itself of the currently selected unit, you remove it from the group.  You can add a unit to the current group by shift clicking it.
 * Ctrl click Crtl click on a unit to select all units of that type visible on the screen (obviously, up to the group maximum of 12). If you ctrl click on one unit in a group of units, all units of that type in that group will be selected.

Protoss

 * P - Probe
 * D - Dragoon
 * Z - Zealot
 * K - Dark Templar
 * T - High Templar

Terran
Command Center
 * S - SCV

Barracks
 * M - Marine
 * F - Firebat
 * C - Medic
 * G - Ghost

Factory
 * V - Vulture
 * T - Siege Tank
 * G - Goliath

Starport
 * W - Wraith
 * V - Science Vessel
 * D - Dropship
 * B - Battlecruiser
 * Y - Valkyrie

Nuclear Silo
 * N - Nuclear Launch

Terran
Basic
 * U - Bunker
 * C - Command Center
 * S - Supply Depot
 * B - Barracks
 * R - Refinery
 * A - Academy
 * E - Engineering Bay
 * T - Missile Turret

Advanced
 * F - Factory
 * S - Starport
 * A - Armory
 * I - Science Facility

Addons
 * S - Comsat Station (To Command Center)
 * N - Nuclear Silo (To Command Center)
 * C - Machine Shop (To Factory)
 * C - Control Tower (To Starport)
 * P - Physics Lab (To Science Facility)
 * C - Covert Ops (To Science Facility)

Protoss

 * N - Nexus
 * G - Gateway
 * P - Pylon
 * A - Assimilator
 * Y - Cybernetics Core
 * F - Forge
 * C - Cannon
 * B - Shield Battery
 * S - Stargate
 * C - Citadel of Adun
 * T - Templar Archives
 * R - Robotics Facility
 * O - Observatory

Universal

 * A - Attack (and Attack Move)
 * M - Move
 * B - Build
 * V - Build Advanced (Terran and Protoss only)

Defiler

 * W - Dark Swarm