Who'da thunk it? – spacing is the most difficult aspect of Korean writing. One might have thought it would be a simple task, that word spacing / separation is innate for all speakers of a given language. Apparently that is not so.Read the comments.
In Hanyu Pinyin, it is called fēncí liánxiě 分詞連寫 ("word division; parsing"). Of course, it has its problems, but we do have rules to guide us, viz., zhèngcífǎ 正詞法 ("orthography").
This morning in my "Language, Script, and Society in China" course, I embarked on a discussion of the difference between zì 字 ("character") and cí 詞 ("word"). Although this seems like a simple, straightforward question, it is always one of the most difficult topics encountered in the course — especially for students of Chinese background. It took me a whole semester to get the idea across to the 72 very smart students in my language studies class at the University of Hong Kong in 2002-2003. Even at the conclusion of the semester, there were still some of the students who just couldn't comprehend the distinction.
It is sometimes useful to reflect of the fact that, aurally, the speech stream is continuous, not segmented. The segmentation is something we impose on the stream through cognitive mechanisms – that, I argue, is the computational foundation of language. Thus early forms of writing often consisted of a continuous stream of characters, with no segmentation into separate words. Victor Mair has a post at Language Log that speaks to this, The challenging importance of spacing in Korean: