Audacity

Audacity

Audacity is an audio editor and recorder available for Windows, macOS and Linux operating systems.
In Audacity, among others, you can:

• Record live audio
• Convert records/tapes into digital format
• Mix multiple audio sources together into a multi-track project.

If you are now starting to work with audio, and you need some basic skills to record and edit files, Audacity and its tools is a good option.

The fundaments of cutting

Link to tutorial
Keyboard shortcuts Edit ------- > copy, cut, paste, duplicate, split cut, delete, split delete
Edit ------ > Clip boundaries --> split, split new

Volume and envelope tool

more here
ducking and auto-ducking

Basic effects

Fade in/out
Amplify
Change tempo, change speed, change pitch
Paulstretch
Reverb
Noise reduction ---> reduce and residue
Generating silence or tone