NZB Files Made Simple
An NZB is a list of files that Usenet software can use for downloading.
NZB files are a list of posts that you want to download from Usenet. Most often, they list all of the parts of a single file you want to download. It doesn't sound as powerful as it is, but imagine a 4 Gigabyte video that you want to download. If it was uploaded in 1 Megabyte blocks then it is in 4,000 pieces! If you are browsing a newsgroup, then your Usenet software will just combine all of these and show you 1 listing for the single item that it really is, but what if you wanted to tell someone else about that 4 Gigabyte video? Better yet, what if you wanted to use a search engine like NZBindex.nl to find things that you like and have your software download them? That search engine needs to be able to give you something to help your software find the 4,000 pieces of that video. That something is an NZB.
So, your friend sent you an NZB file for a great post, or you found something on a website or search engine that looks interesting and you downloaded it from them. It's a thin little file that looks almost readable if you opened it (go ahead, it's ok).
Example of an NZB:
It has all of the information for each segment of what you are going to download. This includes the newsgroup it was posted to, the subject, who posted it, the date, and the size of all of the parts.
Now you need software to be able to actually use it to download. The most popular software currently out there for this is SABnzbd. It has a massive user base and is stable, fast, free, works well with indexers, and it's also open source.
Once you have SABnzbd installed and your Usenet account (click here to get one) is configured, you can give this one little NZB file you have to SABnzbd and it will download everything automatically, and even take care of any decompression or repair if it is needed. This can be done by just double-clicking on the NZB and or you can give it the URL so you don't even need to download it, this just depends on what is easier for you.
That's it, they are pretty simple. They provide an easy way to tell other people about large files. They aren't the files themselves, but a condensed list of them that your software can use to get the actual file(s). Once you give the NZB file to your software, the process is totally hands off and as automatic as if you had double-clicked on something to download from a newsgroup.
As you can see, they make web-based Usenet search engines and indexers possible, and can make your downloads and sharing your finds with friends much easier.