I would like to try to highlight a couple of points that have been made by others that may not have gotten as much attention as I would like to see. What you get is what you mean Someone I think Richard Kinch described the distinction between something like LaTeX math and word processors as a distinction between What You Get Is What You Mean versus What You See Is All You Get. Let me try to illustrate with a somewhat contrived example. You might use italics in some document to for emphasis for foreign words for mathematical variables for titles of books for names of ships and so on. When you use italics for emphasis you mean italic something different than when you use it for some Latin phrase. When you are engaging in writing as opposed to formatting you write what you mean. You might write I really emphmean this; it's not just foreignpro forma. code When you are writing you are focusing on the content and meaning. You are deferring decisions about how emphmean and foreignpro forma will be rendered until you are in the mood to deal with such things. Now suppose that you (or an editor) decides that things like pro forma should not be italicized. By writing what you mean you can easily say that foreign be non-italic. But if you had done this with a word processor and had simply italicized both usages you would be in deep doo-doo going through an un-italicizing all of the foreign expressions. Now modern word processors have introduced style sheets that would allow you to do things as I've described but they are rarely used and not nearly as robust powerful and natural as in LaTeX math . Reusing others' solutions This separation that structural markup allows along with the flexibility to define your own macros (like foreign in the above section) means that solutions that others have found can be reused. For example if someone works out a way to draw the kinds of phrase structure diagrams that linguists like or tools that make it easy to write chemical equations Or nice way to handle breaks that are smaller than a subsection or work out marginal notes in the style of Edward Tufte's books this can (and often are) shared and improved upon by themunity. (Indeed all of the examples above are taken from packages available on the Comprehensive TeX Archive Network (CTAN). (CTAN predates predates the Perlmunity's CPAN.) Update The content below has been added after the original answer Saying what you mean can be hard There is no doubt that getting started with a What You Get Is What Mean system is harder for most people than getting started with a What You See is All You Get one. A good chunk of that extra work is because you now have the responsibility to make your meaning clear. Let me give an example. The dot followed by whitespace . you might write in normal might have one of three different meanings. Let's consider three cases where we might a dot followed by white space (dot-space). Sentence final punctuation as in The cat is on the mat. The mat is ... code In an abbreviation made from initials as in The . operative disemboweled the ... code The space after the dot in Dr. Smith should not be larger than spaces between words (and may even be smaller) but most importantly never break a line there if you can at all avoid it. Contrasting 1 and 2 is really useful. The space after the dot should be treated in opposite ways for those two different meanings. When looking for good places to break lines 1 is a good place and 2 is a terrible place. We never want to see anything like Some blah blah whatever and so Dr. code Smith was annoyed that she was expected code to ... code So back when intelligent and trained humans were figuring out where to put in line breaks this could all be done well. But now to get it right the only human in the process needs to tell the system which dot-space they mean. TeX has some rules for guessing but those rules will miss lots of cases and so you have to tell it which kind of dot-space is meant. You can't always let it guess the meaning on its own. The designers of word processors certainly must be aware of these different meanings of dot-space. And TeX's algorithm for line breaking are not encumbered by patents so in theory word processors should be able to as good paragraph setting as TeX does. But in practice they don't have the freedom to use sentence final dot-spaces as good places to break lines because they have to worry about breaking in a Dr. Smith case. Unless the human tells the software what a dot-space means they can't make use of information it doesn't have. Word processors have meant things that might otherwise have been processed by a professional aren't. And so their results are crappy because to do it right someone has to be careful to say what is meant italic .