As the parent says, this sounds like a loaded question. In fact, it sounds just like som marketing departmetn which wants to promote some IDE is trying to gathe

As the parent says, this sounds like a loaded question. In fact, it sounds just like som marketing departmetn which wants to promote some IDE is trying to gather reasons and possibly features which need to be added to some "competitor" IDE, in order to gather more market share. I write that because to me, the interest to actual answer to the question - why people use these open-source editores - seems somewhat thin. But, as somebody who uses Emacs, why not use the attention for some Emacs marketing. Before going on, I use Emacs mostly since about 22 years. I am also occasionally using vi (mostly for system administration) or mg (which is a very light-weight editor with basic emacs keybindings). I've also used a host of other tools, for example in some work environments there was really no other alternative than to use Visual Studio, or Eclipse, and in some the most practical thing to use was notepad++. So, why Emacs? At first, and something that might be interesting to beginners, basic editing in Emacs, such as to produce similar results to using notepad++, is actually quick to learn. It has a nice on-line tutorial and very good interactive documentation. The fundamental philosophy it has is that basic text editing is modeless, that is, one uses a (possibly large) number of key combinations to modify text, and the basic combinations are universal. And this is already the main difference to vi/vim, where the meaning of basic key commands always depends on the mode. Emacs does have modes, however, for advanced commands which modify different /kinds/ of text. Emacs supports a large number of programming languages out-of-the-box, which includes anything you need to write for documentation. This saves a lot of time when setting up projects. It is also very quick to set up additional packages and modes. Emacs and vi/vim both are based on the notion that code is text: They are optimized for text editing, and in my experience this is absolutely the right thing to do. I had the dubious pleasure to use several systems which use code as kind of point of entry to some kind of database or graphical system or whatever, and these are, universally, just a pain in the ass. Compared to IDEs, Emacs loads and starts very, very fast. In cases where one want it even faster and don't need that many features, one can use emacsclient, or the mg editor, or, of course, vi. It is also possible to use Emacs in a text terminal, which is invaluable for remote work on servers or embedded systems, and it also has good support for the shell's job control: Running in terminal mode (starting with the "-nw" option), Ctrl-Z will bring you to the shell, and "fg" will bring you back to your Emacs session.