“Any man who would letterspace lowercase would steal sheep.”

The headline is rumored to be a quote from the German Typographer Erik Spiekermann paraphrasing American Typographer Frederic W. Goudy‘s

Any man who would letterspace blackletter would shag sheep.

Dear web page designers!

Whoever told you differently:
letter-spacing: -1px or -2px is no good choice, because the word kerning quickly becomes keming with negative letter-spacing and the readability is worse than with the default letter-spacing.

Example of a sentence with completely messed up letterspacing(← Do you see why?).

There is no excuse for it, even Google knows that:

(take a close look at the appearance of the search results page)

The designers of the fonts you use on your web pages put much work and thought into it, please don’t ruin it. If you want a more compact look, change the font stack and use different fonts – but

Please do not mess with letter-spacing. Ever.