For users of Windows 98, ME and 2000, legacy versions of Audacity are available on the Legacy Windows downloads page.
For users of Mac OS 9 and Mac OS 10.0 through 10.4, legacy versions of Audacity are available on the Legacy Mac downloads page.
You can also obtain Audacity as a CD image file or purchasable CD. Note that these are often not the latest version of Audacity.
To build Audacity yourself, download the source code.
You may copy, distribute, modify and/or resell Audacity, under the terms of the GNU GPL.