HARLEY HAHN'S USENET CENTER
File Sharing Tutorial
In this section, we'll discuss, in general terms, the types of data used for Usenet file sharing. To start , we will define the most important idea of all.
A FILE is a collection of data, referred to by a specific name, residing on a storage device. Files are stored on hard disks, CDs, DVDs, flash drives, memory cards, and so on. Broadly speaking, there are two types of files: text files and binary files.
TEXT FILES contain only printable characters, that is, letters, numbers, spaces, tabs, and punctuation. Sometimes text files are called ASCII FILES (after the American Standard Code for Information Interchange). If you look inside a text file, what you see is readable by a human being. For example, the articles that are posted to Usenet discussion groups are text files, that is, they contain words and characters that are typed by people to be read by other people.
BINARY FILES or BINARIES, on the other hand, contain non-textual data that makes sense only when read by a program. For example, if you were to look inside a music file, it would look like gibberish. A music file only makes sense when interpreted by a music program. Thus, all MP3 files (music files) are binary files. Other examples are executable programs, images, video files, word processing documents, spreadsheets, and databases.
Almost all the files that are shared via Usenet are binary files. Thus, the best way to understand Usenet is to think of it as a data distribution system is used in two completely different ways: for discussion forums using text files, and for file sharing using binary files.
I mentioned in the previous section that there are well over 100,000 Usenet newsgroups. Actually, almost all of them are TEXT GROUPS used for discussions. About 2,000 are BINARY GROUPS used for file sharing. However, since the binary files being shared are much larger than the text files used for discussions, the vast majority of the bandwidth and storage space used by Usenet every day is used for file sharing.
For example, a typical text-based article posted to a discussion group might run, say, 1.5 KB (kilobytes), that is, about 1,500 characters. A single music file posted to a binary group could easily be 4-5 MB (megabytes), and a typical movie video posted to a binary group, might be 400-500 MB. Indeed, some people post the contents of DVDs that range in size from 4 GB (gigabytes), for regular DVDs, to more than 10 GB for Blu-ray DVDs.
To put this in perspective, it would take 300,000 discussion articles, each 1,500 characters long, to use up the same amount of storage space as one 450 MB video. Even more extreme, the contents of a 10-gigabyte Blu-ray DVD require more storage space than 6.6 million such text articles.
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