DotA vs Warcraft III
That’s right, they are not the same. I just had to voice this out: DotA is not Warcraft III. It’s now starting to vex me every time conversations invariably follow this routine:
“Warcraft ta bai!” (Let’s play Warcraft man/dude!)
“Unsa na hero imo gamiton? Puck?” (What hero are you going to use? Puck?)
It’s at this point that I do a mental slapping of my forehead.
Then for the one millionth time I go:
“No, Warcraft na Warcraft! Not DotA!” (Translation not needed, you get the point.)
Warcraft III is a real-time strategy game that involves multiple units under your control and more importantly, base-building. DotA on the other hand is a mod, which is short for the word modification; it alters several aspects of Warcraft III and is in fact, a totally different game. The absence of base-building is its most prominent alteration.
What is a modification? In a nutshell, modification is an unofficial modular software developed by individual/s that alters some or all parts of the games they are installed to. The amount and degree of changes vary from simple tweaks to total conversions (or TCs for short).
An example of a simple-tweak modification would be the Duct Tape mod for Doom 3. The mod attaches a flashlight to selected weapons. This was made in response to the popular complaint of the game’s unwieldy implementation of its flashlight.
This screenshot, on the other hand, will fully explain what a total conversion is.
Modifications are dependent on their base games too; they cannot run without the base games that they alter. Think of the base games as coffee and the modifications as coffee creamers. DotA cannot run without Warcraft III installed.
Warcraft III: coffee. DotA: Coffee Mate. 
To wrap this up here’s a Wikipedia entry about mods.
