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What are seeds, peers and leeches in Torrents' language? - Quora

Torrents (file sharing services)

BitTorrent (product)

File Sharing

μTorrent

More Answers Below

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Ankush Jain, CS Student

18.9k Views

Thanks for the A2A.

What are torrents? Torrents are a way to distribute files.

Search for questions, people, and topics

But what are seeds and peers?

To understand all this, first let's take a look at a simpler method of sharing files HTTP.

HTTP is used when you download files from a website using your web browser, or something like

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What are seeds, peers and leeches in Torrents' language? - Quora

Internet Download Manager. (For example, when you download Adobe Reader, or drivers from

manufacturer's website, it's usually via HTTP).

How HTTP works is pretty simple. Let's say Microsoft wants to distribute a 30day trial of

Windows 10. They buy a computer, connect it to internet, place a copy of the Windows 10 image

on its hard drive, and configure some software (like Apache web server) to allow people to

download the image.

When a user wants to download the image, he sends a request to Microsoft's web server. The web

server starts replying with the Windows 10 image data as fast as the internet link between the two

of you permits.

When the image is being transferred between the two (server and user), two things are happening

simultaneously upload of the image from server, and download of image to the user's PC. (Think

of upload as a person speaking on the phone, and download as a person on the other end taking

notes).

This is a pretty simple and convenient method of file sharing. But it has some drawbacks.

1. Someone needs to set up a server and buy a very fast internet connection. If the server's

internet connection is 500 kb/s either one client can download at 500 kb/s, or if two clients

are downloading, the speed will be divided between them and each of them will get 250 kb/s.

If one of the clients has a slow internet let's say capped at 50 kb/s, the other client can

download at 450 kb/s. Similarly, if 15 clients with fast internet connections are downloading,

none of them will get a speed of more than 33 kb/s (500/15). Suffice it to say, Microsoft's

servers have a very fast internet connection.

2. It's vulnerable and easy to block. If you don't want your users to download Windows images,

you just have to block Microsoft's sites. I can't think of why nonprogrammers would want to

block Windows image downloads, but in case of censored content (like Government crimes),

or illegal content (like pirated movies), or both (NSA leaks), we can see why the government

would want to block it.

Now let's see how torrents solve these problems.

Let's say you are a person with access to proof of government crime (1GB of files). You tried to

host it on a website, but the government blocked it. You now want to share it with rest of the world.

What you do is you create a torrent of the file. A torrent is basically a very small file containing

details of the files (names, file sizes, MD5 hashes etc.) that are shared using that torrent file. You

can create it easily using your torrent client (uTorrent, Azureus, Transmission etc). You also have to

add tracker details to the torrent file. A tracker is a server whose job is to distribute peer lists to new

peers (we'll discuss this in detail).

You host this very small torrent file on some torrent sharing website. People who want to download

your government crime proffs go to the torrent website and download the torrent for it.

They then tell their torrent client to download the files described in the torrent. Since there is no

server (like Microsoft's server for Windows image) to download the torrent from, their torrent client

talks to the tracker.

Client "Dude, any idea where I can get these govt. crime vids?"

Tracker "Idk man, try these people" (gives client a list of other people interested in downloading

the file)

Client "Btw, add me to your list. Just in case anyone's interested" (gives him his IP address)

Tracker "Whateva, bruh"

Your torrent client goes to each of the people in the list so obtained, and asks them if they are

interested in sharing the files. Let's say out of the 48 people in the list, 4 say they have File 1, 3 say

they have File 2, and 6 say they have both the files. 9 say that they don't have any files, but would

like to download any files you have. The rest don't respond (maybe).

So you start downloading File 1 from all of those 4 + 6 people who have it, and File 2 from all of

those 3 + 6 people who have it. Since you're downloading the file, they are uploading it on the other

end of the internet connection. Now since you downloaded it and used other people's internet (in

addition to your own), it is your moral responsibility to allow other people to download it from you.

Thus a torrent is a group of (100s or 1000s or more) people collaborating and giving each other

pieces of the file until everyone has a copy of the entire file. It starts with the person who created

the torrent simply uploading it until many people download, and then they upload it in turn and the

torrent spreads.

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What are seeds, peers and leeches in Torrents' language? - Quora

So if the file is 1GB in size, the creator has to upload atleast 1GB for it to spread. Ideally, he'd

upload about 34GB, and that would give him 34 more friends, who'll help spread it further.

This is why your torrent client is both downloading and uploading the torrent file. Downloading it

so that you can use, and uploading it so that others can also access the file.

All people engaged in the activity of sharing the torrent are called peers.

The people who are uploading are called seeders.

The people who are downloading are called leechers.

A lot of people, however are both downloading and uploading at the same time and can be called

both (downloading parts they don't have and uploading the ones they do).

If the number of seeders is more, you are likely to download the file faster. If the number of

leechers is more, the download is likely to be slow.

Advantages of torrents:

1. Central servers (i.e. the website where you upload the torrent, and the tracker) don't have to

share a lot of data. Both torrent files and peer lists are very small in size, hence these servers

don't cost that much to set up and maintain.

2. Difficult to block since no central server is involved in the actual distribution and sharing of

the files, it is difficult to block given its distributed nature.

Thus you may realize why uploading (Seeding) is so important to the concept of torrents. You are

able to download only because someone else was uploading it for you. A torrent dies quickly if

people refuse to upload. (It may also happen that no one wants to download the torrent any more,

and people who are willing to upload don't find any takers, and after some time they give up and

stop uploading that particular torrent).

Written Jan 5, 2015 • View Upvotes • Answer requested by Harish Chandasana

Kush Tripathi, Quorageous, Quora inspires, conspires, respires within me

25.2k Views

Seeders are people who have already downloaded the file and are uploading them. The more

seeders the faster the download will go.

Leechers are people who are sharing what they have and are downloading what you have.

When searching torents, always get high seeded torents. If there are no seeders, you will never

finish the download, no matter how many leechers there are!

More leechers there is the slower the download, so try to find a file with many seeds low leeches

Written May 30, 2013 • View Upvotes

Dan Lewis, Founder of prelaunch startup

5k Views

You aren't really "seeding a torrent", you are seeding the file to which the torrent points. "Seeding"

means that you have a completed version of the file, and you are making it available for others to

download via the torrent.

Seeding is the opposite of "leeching", which is the process of downloading the file from others who

are seeding the full file or just sharing the parts they have already downloaded while waiting for the

rest.

Written Mar 4, 2013 • View Upvotes

What Are Seeds, Peers, and Leeches in Torrents' Language?

What Are Seeds, Peers, and Leeches in Torrents' Language?