If you are a Korean student, it is understandable that your sense of the world of computers and the internet might be distorted. For reasons too complicated and tragic to explain here, Korea has been trapped into using Microsoft OS and software almost exclusively, as well as a very limited number of portal sites with specific services offered.
This is not the way the internet works for the majority of the planet you live on. We have a great deal more diversity out there in the rest of the Net than you have in Korea’s net. (And freedom, too: we don’t need to give our ID numbers to do simple things like register on a website, comment on a news article post, and so on.)
You need to be aware of the fact that these differences exist. This diversity is important, because out there in the rest of the world, there is also a huge variety in the kinds of OSes people can and do use: not just Windows, but also Linux, Mac, and other OSes like OpenSolaris, FreeBSD, and more.
In most of those OSes, because internet standards are established and followed, users can do all the same things in any browser. Likewise, files formats that are popular are used, to ensure that anyone can open a file if they need to do so. Proprietary file formats — the kind you can open only with one program, such as HWP-format files — are less popular, especially for common jobs like word processing.
If you are emailing files to a non-Korean, you should be aware that .HWP files may be completely useless to them, for two reasons. This may shock you, but remember, Hangeul–the computer program by Hancom, I mean–is a specifically Korean program, and not really used anywhere else except by Koreans abroad. (In fact, I know a number of Koreans who dislike the program and refuse to work with it, since it lacks many important functions available in most modern word processors.) But more importantly, if someone does not have Hancom’s software installed, then your HWP file is impossible to open… and thus useless.
You might pause and say, “But there is a free Hancom reader! They can download it here!” Sure, that’s true… but links die. And even if a HWP-reader exists, it only exists for Windows OS. As far as I know, there is no free Hancom HWP reader for Linux, the OS I use, or for the Mac OSes, or any of the other various OSes that people all over the world choose to work this. (And Hangeul for Linux was both poor-quality and very expensive last time I checked.)
When you are sending files to people, the burden of file compatibility is on you. You cannot make any assumptions about file format accessibility. Therefore, you need to consider the norms that exist online; while it is normal to send a Korean file to a fellow Korean in HWP format, it is plain stupid to send that file to a non-Korean, and expect them to bear the burden of file compatibility.
(Surprising examples of this stupidity are easy to find: several universities put job application forms on their websites in HWP, while advertising job positions to people abroad.) Likewise, in some word processors, the .DOCX format is not handled well. (The OpenOffice software I use in Linux, the best word processor software for that OS, doesn’t handle it perfectly, for example.)
Nothing makes you look less professional then sending someone a file he or she cannot open. Once again: while there are Hangeul viewer programs for Windows, again, outside of Korea (and among Westerners in Korea) there is a much greater diversity of computer types and operating systems (Mac, Linux, and more) than among Koreans in general.
Therefore, you need to stop and think about file formats when emailing a file to a non-Korean, whether overseas or within Korea. Of course, if someone has told you that HWP files are okay, then that’s fine. But you cannot assume this will be the case. In fact, you should assume this is not the case until someone tells you otherwise; when you don’t know what formats are okay, here are some guidelines that pretty much indicate the norms in the English speaking world:
DON’T USE file formats that are NOT (or not yet) commonly accepted worldwide: .HWP, .DOCX
DO USE file formats that ARE commonly accepted worldwide: .DOC, .RTF, .TXT
Hancom’s Hangeul program can export to at least some of these formats–definitely to .DOC and I think to .RTF as well. I can’t remember whether you need to use a SAVE AS or an EXPORT function, but it should be in the FILE menu of the program.
If you need a free word processor that handles both these file formats, and English text in general (and spelling checks particularly) better than Hancom’s software, I recommend Open Office. It’s free and very good quality.