Audacity is free, open source, cross-platform software for recording and editing sounds.
How it is useful to technical communicators:
Audacity can be used to add/edit audio when working on video assignments. It provides more audio manipulation techniques that are not available through video software.
Where you can learn more about it:
You can learn more about Audacity and download the software through the Audacity website.
Other software like it:
Adobe Audition