There are many different versions of Eggdrop available for download from various FTP sites. Three major versions of Eggdrop are currently in use - 1.1.5, the 1.3/1.4 series, the 1.6 series. Other versions include the 0.9 series, 1.0 series, 1.2.0, and Eggdrop2, but these aren't used much any more.
1.1.5, which is now more than eight years old, is used by some experienced users who have become comfortable with that version and may have spent much time applying their own modifications to make it work the way they want, and therefore don't wish to move to a newer version. Some people consider 1.1.5 to be the most stable and least buggy version of Eggdrop, in no small part due to the failure of 1.2 to gain acceptance and many bugs early on in the development of 1.3 series. But later versions of the 1.3 series were more refined and better overall than the ageing 1.1.5.
Before 1.6, the 1.3/1.4 series was the main version of Eggdrop in use. The last version in the 1.3 series was 1.3.28, before it was renamed and became the 1.4 series as part of a new version numbering system (1.4.0 comes right after 1.3.28). The last in the 1.4 series is 1.4.5, and is a very stable bot. Some people who prefer the lower memory footprint and simpler configuration of the 1.3/1.4 bots are still using versions in this series.
But the best version of Eggdrop, for most people, is the current 1.6 series. This was in development for some time (during which it was known as the 1.5 series), so it was quite refined and stable by the time 1.6.0 was released. The current version is 1.6.21, and it is the most complete, feature-rich and functional version of Eggdrop. If you're just starting out with Eggdrop, you should use 1.6.21.
The Eggdrop2 bot was a substantial rewrite of Eggdrop in the C++ language and with an even more modular structure. However, it was considered to be quite buggy, and its developers eventually abandoned Eggdrop altogether as users stuck with the 1.3 series, which was further developed by a new team. Most 1.4/1.5/1.6 series versions are actually newer than Eggdrop2, and Eggdrop2 should not be confused with the upcoming 2.0 series currently in development.
Eggdrop is distributed primarily on FTP servers in tarball format (with the .tar.gz filename extension), with the version number in the filename. The Eggdrop 1.4.5 source, for example, would be named eggdrop1.4.5.tar.gz.
www.egghelp.org's file area contains the latest versions of Eggdrop, as well as important older releases.
ftp.eggheads.org/pub/eggdrop/ is the official site for the latest releases of Eggdrop 1.3, 1.4 and 1.6.
You can download these directly to your shell using the shell's FTP client as described here, but I recommend you download Eggdrop to your system (then upload it to the shell) so that you have a local copy of the config file, documentation, etc. to refer to when needed (you can use 7-Zip to unzip the .tar.gz file on your system). Note that if you download Eggdrop with an old version of Internet Explorer or Netscape, the filename may be corrupted into something like eggdrop1_4_5_tar.tar once it's downloaded. If that happens, make sure you change it back to eggdrop1.4.5.tar.gz.