I've seen people on the Internet stressing a certain word using "*":
I do not *like* it, I *love* it!
I think there is no such punctuation as "*". So I'm wondering if I can use some other way to achieve the same goal in traditional English. I've tried quotation marks but then it sounds like I'm posing ironic effect.
I do not "like" it, I "love" it!
That sentence leaves the impression that I'm loving it in a unusual way.
The classical punctuation to denote emphasis is the exclamation mark.
However, that applies to the whole sentence. It is sometimes possible to draw a word to the end of a sentence to emphasize it instead of the whole sentence:
I love kittens … not!
Or if the word in question is an interjection, put it between dashes:
The dessert – delicious! – had just 200 calories.
Another alternative I have sometimes seen is putting the exclamation mark into parentheses behind the word.
This is the only (!) way of using emphasis.
But in general, emphasis of single words is achieved via formatting, not punctuation.
Historically, this has been italics, or, since, italics are hard to emulate in handwriting, underlining in handwritten documents. With the advent of typewriters, the underlining convention was reused but on computer terminals, underlining no longer works because you cannot shift the carriage position back in a text document (which is how underlining was achieved on typewriters).
This is probably when people began to hint at emphasis by prefixing and affixing a word with underscores: _like this_.
In newsgroups, many people switched to slashes, /like this/. I have no idea where the asterisks come from though.
l̲i̲k̲e̲_t̲h̲i̲s̲, but it's much easier to type _like this_ than it is to fiddle with Character Map.
The asterisks are used commonly on the internet in situations where the writer has no control over how the text is typeset.
Traditionally, such emphasis is added by using an italic or bold face.
This is why "plaintext markup languages" such as markdown (which is used on the stack exchange sites) typically convert *text* into text (or sometimes text).
I'm not aware of a traditional means of adding emphasis purely with punctuation (I imagine that if there was such a way then people would never have started using asterisks for this), though it's often possible to re-phrase things to add emphasis linguistically.
Traditionally, emphasis has always been achieved through italics, but only if you need emphasis on a particular word rather than the entire sentence. Most forums provide the possibility to provide italics, though lacking that, you need to surround the word with *. Despite the fact that it is not preferable, it's perhaps the only way to emphasize without italics or bold typing.
What you are trying to do is mark speech patterns, particularly intonation patterns. Standard English orthography doesn't do this at all, and the various attempts I've seen on and off the Internet, from italicizing to marking out with special symbols, all make the writer look like a poseur more than conveying stress information.
Fortunately this only really arises in blogging and diary writing when you are trying to write in a colloquial speech-like manner. Most other occasions when emphasis matters involve direct speech, and for that purpose we pick adjectives carefully!
Plenty of amazing and informative answers already. However, one option that hasn't been mentioned is square [brackets]!
I personally like this method in mediums or platforms that do not support italicizing, and there are plenty of such platforms, ironically ones that are even involved in heavy use of writing, like some text-roleplaying or play-by-post and collaborative fiction websites.
I do not know how the use of the asterisks, like *so*, started, but I do know that they are used heavily in some text-roleplaying or collaborative writing communities, traditionally to represent actions of characters in the story, though, as opposed to dialogue. Moreover, the asterisks are used on countless websites and mediums to show italicized words after you press Enter or Send, including right here on Stack Exchange! So maybe that's why others use them so much, even when their words don't show up italicized. I personally don't cringe at the use of asterisks for emphasis, or don't find it unacceptable, but it's not my favorite way of emphasis.
And I don't like the use of underscores, like _so_; this just looks wrong to me personally.
The use of the slashes, like /so/, on the other hand, is much more easy on my eyes. However, I would still feel like something's not quite right.
So finally, square brackets are actually formally used to represent the author's additions in a quote. You can see this quite often in good newspapers when the journalist is quoting someone. For example, the article could say, "The burly mechanic said to me, 'The way we do things here [in the basement of his shop] is as follows...'". Or it could say, "The band leader showed me his electric guitar and referred to it as '[his] weapon of mass destruction'"; in this case, the author or journalist is clarifying that the word "his" was obviously not used by the band leader himself, but you, as a reader, will be able to guess that the band leader is quoted word for word otherwise, and he said "my" instead of "his".
So one can argue that we should not use square brackets this way so as not to confuse our readers about the purpose of the square brackets, and while I tend to agree with that line of thought, I also would personally consider my audience and what exactly I'm writing. And I would argue that when we are in a medium that does not support italicizing, like most chat programs today on the phone and desktop computers, we are most probably not going to confuse our "audience" when we refer to [the] thing we love most about, say, action movies. So yes, I'm personally happy using square brackets to emphasize the occasional word, and I find it the most elegant and easy-on-the-eyes way to achieve this in mediums that do not support italicizing.
How about using a single parenthetical? Example: Could Rosa have developed an understanding of 'indifference'?
