If Dota 2 is in your games list and you don't remember recieving it then it is probably the spectator client that everyone gets. Even if you don't own the game, you can still watch games.

While certainly the most prominent name in the genre, DotA did not create the genre. Before DotA, there was a StarCraft map called Aeon of Strife, and DotA built upon its relatively simple concept and built it into a full-blown game all of its own.

It's a competitive arena game. I enjoyed it a lot as a wc3 map a while but after some time I really lost interest. The community is horrible, people expect you to learn on the fly and to keep your mouth shut and then there are full of whiners.

I remember though playing some hacked version of dota with AI that were brutal because they cheated (AI itself was good too but they received more gold and XP) and playing that with a couple of friends on a LAN party was awesome.

Yes, yes I am well aware of that BUT it was DOTA that spawned the genre sure it took elements of Aeon of Strife but it was DOTA that the genre spawned from, just like how Wolfenstein 3d and Doom were not the first FPS's yet they were the games that spawned the genre despite not being the first.

Dota initially started off as a custom map in WC3

During the peak days of WC3 (I should know, I was there) Many players would constantnly make fun of people who played nothing but Dota, saying that it's played by people who are too unskilled and weak to play actual RTS matches

10 years later, this statement is still true

Dota was response for creating the absolutely terrible "MOBA" genre bandwagon, it was also responsible for completely killing the Custom Map scene in Warcraft 3

Speaking about Warcraft 3 :

http://www.desura.com/mods/power-of-corruption
http://powerofcorruption.com/

http://www.desura.com/mods/beyond-the-throne-tides-of-darkness
http://www.hiveworkshop.com/forums/map-development-202/beyond-throne-tides-darkness-32321/

A more detailed history: The very first custom map in the genre was called Aeon of Strife, and was made using the StarCraft map editor. I have not played it myself, so I can't comment on its quality or features, but the map was, much like Tower Defense maps, widely copied. During the heyday of WarCraft 3, one could open up the custom map game searcher and find hundreds, if not thousands, different variations on the map.

About half a year or so after WarCraft 3 launched (random guess) the first DoTa saw the light of the day. It quickly became quite possibly the most popular map simply because it did something very few people knew how to do: it modified the abilities of units, something which was not possible using the map editor packaged with the game. In addition, heroes were, unlike in other AoS's of the era, mostly very low-powered and gameplay thus revolved largely around supporting your own team.

It should be noted that Defence of the Ancients (DoTa - yes, people really wrote it like that) was not the first of its kind - in fact, it would probably not have seen the light of day if another, mostly unknown, map, Valley of Dissent, hadn't shown that it was possible to edit abilities first. I doubt there's more than a handful of people who know about this little tidbit, though. It's only really remembered because Eul, the creator of the original DotA, made a point of fixing the map when a patch broke a lot of triggers.

There were a number of spin-off projects for DoTa, such as a defender/attacker-style map called Stand of the Dwarves and even a sequel map called Thirst for Gamma, but neither really took off and both were quickly abandoned.

When The Frozen Throne was released one of its most anticipated features for custom map aficionados (such as me, at the time) was the ability editor, which is just what it sounds like. Combined with a number of other now-official features, such as the ability to change the level cap, people went completely nuts making maps with modified abilities.

DOTA All-Stars was one of these, and it was pretty much the most popular game from day one, completely crowding out the now-obsolete and rather clumsy DoTa, which I believe ceased updating at that point anyway. As far as I know the original creator had nothing to do with the new DOTA All-Stars, which was more or less a copy of the original map but with more heroes that were slightly more powerful. I never played this version; I was busy with other maps at the time.

Interestingly, DOTAAS actually duelled for a long time with another, very similar, map I can't recall the name of, but as history has shown the other map lost. DOTA All-Stars is the template from which all current-generation MOBAs are made; not bad for a map with enormous interface lag, minimal player character depth, little player interaction and a server that tends to drop a player per game, give or take.
Hardly; as I recall there were few clones of it around, oddly enough. There was plenty of variety for at least a year, but eventually the game gets old and people move on. The only people who stuck around were those who wanted to play DotA.

You only need steam to play Dota 2. Dota 1 is a map of warcraft 3. Basically its a 5vs5 game where....I can't describe it, look up moba.

It was a map in wc3 that got really popular for some reason.

Then MOBA's came out and they got popular for some reason.

Then Valve decided it wanted a piece of the pie and shoved the entire pie down it's fat mouth and created the oh-so-original title of "Dota 2"

And that's why we have Moba's today, because of Dota...and the most annoying twats in the gaming community.

Valve actually hired the dev of either the original DOTA map or DOTA All Stars, IceFrog, so that's why they get away with using the name DOTA2.

Indeed.

The wow community is far worse Imo.