Hangul Word Processor, or HWP for short, was developed by a very innovative Korean company called Hancom Inc. It is the official word possessor software for Korea. To support local technologies, all Korean government agencies and many universities use HWP as their standard word processor. Similarly to Microsoft, there is Hangul Office, too.
You may have someone send you a HWP file and only to realize you cannot open it. Please do not panic as one doesn’t have to buy or download the full program to open such a file. There are several free viewers that you can easily find online.
One of these is available here: