I think he means kerning, but the way he describes it, he gives the definition of tracking... and if we're talking about this in the context of the web, well, you really can't kern on the web. Adjusting the tracking (with letter-spacing in the CSS) is about all you can do. So really, it depends on the font. If the font has nice ligatures, I think it often looks better left as-is. You wouldn't encounter this problem with proper kerning... which is why I hope that's what he's referring to. :)