Peer-to-Peer - Introduction
Peer-to-Peer(also known as P2P) is one of the most known ways of sharing files across the internet. BitTorrent(also known as BT) is probably at the top of the list when it comes to sharing files, simply because of ease, no cost, and a highly dedicated community. It’d be a shame if you didn’t know how to use these tools because a lot of products actually now have a BT mirror to make downloading faster(and cheaper for them) because you’re collectively downloading from a large number of people.
The Big Picture
Essentially, P2P is a large network where everyone connects to each other rather than connecting to a central server.
Central Server Network
A Central Server Network is a network where everyone connects to one sole central server that contains everything you need. Often this is the best route when thinking about networks such as a file(or code) repository, website, etc. Think of times when everyone is trying to get to the exact same thing. However, when it comes to file sharing it can be a huge problem. You’re not talking about limiting people(such as in code repository where only designated designers get there) and you’re not talking about websites(where traffic is very minimal in size). You’re talking about sharing files they may be hundreds of MB’s or possibly even hundreds of GB’s! That’s a lot of bandwidth we’re talking about.
P2P Network
A P2P Network is a network where there is no central server. In fact, no real server even exists at all. The only thing that exists are other users. Basically, you end up having files(often known as trackers) that keep track of who is downloading / uploading a specific file. Then, once you go to try to download that file, you’re added to that list and you join in on the downloading / uploading. Bandwidth is now simple between user-to-user, hence “peer-to-peer”.
Obviously P2P helps the users because instead of a central server that gets really busy and slow, or one that charges fee’s, if a lot of people are uploading(seeding) the file you are interested in, it can go extremely fast(no faster than your own internet speed of course). However, if the file you are wanting isn’t very well known so only a few people are uploading(seeding) it, then it can go extremely slow where as if the file was on a central server, it probably wouldn’t take a week to download the file.
Terminology
Torrent
A torrent is a metadata .torrent file that provides data(or information) about another file that contains the data that you really want. For instance, you download a .torrent from a website, which you then feed to a BitTorrent client application that then uses that .torrent file to start downloading whatever it is that you really were trying to download.
Peer
A peer is another computer(often, a user) that you connect to over the internet to transfer data back and forth with. A group of peer’s is how people are able to torrent(download) files back and forth from each other. When you are torrenting, you are considered a peer as well.
Seed/Seeder/Seeding
A seed is a computer that has the full complete copy of a specific torrent. Seeding is the act of actually uploading to others. A seeder is someone who let’s their computer seed. A seeder can control what they seed, the duration of the seeding process, the bandwidth, and more.
Reseed
When a torrent gets to the point that it has zero seeders. What happens is that there are people trying to torrent the file, but the file is incomplete because there are no peers with the full complete copy of the file. Therefore, a request to reseed is made. Either the person who posted the torrent or someone who received a full complete copy of the file, must start seeding again so others can keep the file alive.
Share Rating
Your share rating is simply a ratio of how much you share(seed/upload) versus how much you download(torrent).
Tracker
A tracker is a server residing on the internet that manages a list of peers. When you open a torrent, your BT client connects to one of the tracker servers and receives a list of peers that it should try to connect to.