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Hey! I invented the magnet link, almost 10 years ago.

Great to see it still evolving and spreading, based simply on its loosey-goosey merits.

Finding this sort of thing always makes me stop short and realize, "Oh yeah, no matter how smart I think I am, there are people a million times more accomplished than me on HN." Not to make me despair so much as take care to avoid blathering the first thing on my mind before reading and considering what others have said.

The 'magnet URI' was merely the right suggestion, for a tiny sliver of shared convention, at the right time.

You can look at the original writeup – http://magnet-uri.sourceforge.net/magnet-draft-overview.txt – and find a goofy ad-hoc mechanism where local software interested in 'magnet' links listened for localhost web hits, in a certain port range, rather than fighting over the 'magnet' URI scheme handler. That could be seen as either a blathering kludge or a very early attempt at 'web intents'.

I don't know if any code other than my demo ever implemented that localhost-handler trick. But the main idea – of a generically-named URI that was descriptive rather than location-centric – had its own legs. It spread from software to software, even without any formal spec stewardship/revisions. A key step for its longevity, when 'magnet' was adopted to wrap the 'btih' identifiers for DHT-based torrent tracking, happened long after my attention moved elsewhere.

I'd like to think the continuing adoption was because the original draft, even though crude and incomplete, had the right mix of a familiar/defensible URI syntax, wide-open descriptor semantics, and a catchy name/icon.

Good ideas don't have inventors so much as they have stewards. Keep trying and one day such a thing will find you. :)

It's weird, I've been seeing it for years but I never understood what it is. I still don't really.

But when I click on the magnets things seem to download immediately. So looks like you built something pretty amazing. Congrats!

It's basically a URI that contains the torrent hash enabling a client to find peers through a decentralized network such as DHT instead of requiring a tracker. I believe you can append trackers and other info to the URI as well, but I'm not sure about that.

Note: DHT = Distributed Hash Table

The other two comments are (correctly) describing what a magnet link is in the sense of its implementation. On the off chance that you wanted a more abstract/basic description, a magnet link is defined by what you're linking to, as opposed to where it is.

This is kind of cool, because a file can change locations (how many times have you seen a dead link/File Not Found?), and with a magnet link, if you have a file that matches the description, you can be reasonably certain that you've found the right file (unlike the URIs you're familiar with, which can change the content stored at each location). On the flip side, actually finding the file from the description is a bit more complicated, but as you can see, it's still pretty easy for the user when implemented correctly.

It's better for TPB, because they're no longer telling you 'where' the file is, just what it 'looks' like. Legally, I'm sure that makes some difference.

AFAIK, it's a torrent for a torrent; a DHT implementation. The URI for the magnet link has all the information it needs to find peers and start downloading the data, the first datum of which is the torrent file.

Ups to you! I think (and hope) that we haven't seen the end of magnet yet. I wish the scientific community would start using magnet links for paper references, instead of archaic bibtex layouts combined with online publishers who charge 30 dollars without adding value.

When multiple downloads of the same file are available it's usually beneficial to see and select the one with the highest number of seeds. If DHTs become the norm, will it still be possible to obtain and use such data?

If I understand magnet protocol correctly, it doesn't matter. If two files are the same, they have the same hash, so the system (DHT) cannot tell them apart.

If the files are different (e.g. 256 and 320 bitrate mp3 files), then that is a completely different problem.

I should have been precise: how does one determine the number of seeds for a given piece of data e.g. when the same movie at different resolutions is available, that is, different hashes?

I think that when you use a magnet link it either includes the tracker (which is the part of BitTorrent that tracks the seeds) in the text of the link or uses a more sophisticated technology called a Distributed Hash Table.

uTorrent 3.1 added support for BEP33 (DHT scrape), so apparently the answer is yes. http://bittorrent.org/beps/bep_0033.html

Expect a knock on your door from the entertainment mafia's logic-focused lawyers.

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