Audacity is the most popular free, open source audio editor/ recorder avalible. Audacity works with all platforms, including Windows, Mac, GNU, Linux and more. However, this podcast software is more intended for editing and recording than publishing. So many people use this program to create their podcasts but use other programs or services to publish them.
Audacity works with a variety of audio formats, including open source formats like ogg but is not compatible with proprietary formats like wma or aac. The recorder can record from almost anything, including from a microphone, line in or anything playing through the sound card.
Recording/ Importing:
With Audacity, you can record just about anything. And since you can record through a line in, you can digitize recordings from tapes, records or from a midi device. It can also record from a microphone and anything playing on the sound card, so any sound your computer will play can be recorded.
You can import wav, aiff, au, ogg and mpeg 2 & 3. It can export wav, aiff, au and ogg and can create CD quality wav and aiff. As mentioned above, it does not support proprietary formats like wma or aac, which are owned by Microsoft and Apple. However, mp3s are pretty much playable anywhere.
Editing:
Audacity offers a good collection of editing tools including mixing, cropping, cross fading, noise reduction and much more. It also has effects like echo, fade, modulation, normalization, reverse and tempo. This program has a waveform display, volume sliders and a mouse zoom for easy and quick edits. Although this is an adequate program, it does not include as many editing tools and effects as Propaganda.
Publishing:
This software does not include publishing tools; you have to go through another service like PodBlaze to publish your podcast.
Ease of Use:
Audacity is easy to use, although it would be nice if it had a drag & drop tool and right click edits like Propaganda.