Downloading from newsgroups is a little more challenging than downloading from a regular web or ftp site. There are two main reasons for that and both of them are related to Usenet’s underlying principles, so they will not be completely resolved anytime in the near future…
The first reason is that Usenet was not designed for downloading from newsgroups; it was designed as a medium to share ideas and opinions in text form, similar to a message board. This limits the size of each post on Usenet and prevents posters from posting big binary files that are ready to download.
The second reason is the Usenet organization itself. As posts hop on and off numerous servers around the world, some of them get dropped or lost in certain not-so-well maintained networks. This results in missing parts from the posts and makes combing parts and retrieving useful information a little more difficult.
Having said that, let’s go over the steps necessary for downloading a file of about 20MB, for example. First of all, the poster most likely has archived the file in order to save bandwidth. So from a single file it was archived into 5 archive files – rar, r01, r02, etc. Each of the files is about 4MB in size.
Most likely the poster has posted the archived files to a certain newsgroup using a specialized posting program which has split each of the files into 8 smaller pieces – rar 1/8, rar 2/8, etc. In order to download the file, the user has to download and combine all 40 parts on his or her own machine. Some posters post parity check files, called par’s which can replace any one of the missing archive files (in case it was lost somewhere around Usenet).