Hi,

I've always liked the style of old textbooks, where important terms were emphasized not by bold or italic, but extra spacing between letters. How to achieve this in ConTeXt?

See the manual and search for '\streched'. But you should know what you are doing. Letter spacing should only be used in black letter fonts, on a typewriter and in (small) caps. Also go to the wiki and use the google search there with 'streched'. You'll find more some information there. Patrick