Software

DAWs (Digital Audio Workstation)

These programs allow you to manipulate sound, midi, use effects on audio, sync audio to video, as well as many other functions specific to each. Many of these are preferential and are just tools in a sound designers arsenal (and are not inherently better than each other) Listed in no particular order:
 * Avid - Pro Tools
 * Cockos - Reaper (Product Page)
 * Apple - Logic X
 * Ableton - Ableton Live
 * Steinberg - Nuendo
 * Steinberg - Cubase
 * Audacity
 * Renoise
 * Bitwig
 * Presonus - Studio One
 * Sony - Sound Forge
 * Adobe - Audition