In text messages and e-mails to your friends, anything goes. In more formal writing, though, readers expect to be treated as colleagues, not pals. And they expect to see well-considered, grammatical sentences and well-chosen vocabulary.

Words that an up-to-date dictionary has tagged slang, used in e-mail, or the like probably do not belong in writing intended for anyone except close friends. The same goes for words or uses of words that feel informal but aren’t in the dictionary at all. These are probably too new or too far from the mainstream to use in most kinds of writing:

The Gates Foundation gets no props for its work on malaria.

The Gates Foundation gets no respect for its work on malaria.

It’s a dis to local farmers growing healthy food that agribusiness receives way more federal subsidies than they do.

It’s an insult to local farmers growing healthy food that agribusiness receives considerably more federal subsidies than they do.

Words tagged colloquial or informal do not belong in research papers or any other type of formal writing:

According to Gates Foundation statistics, 85 percent of those who die of malaria are kids under the age of five.

According to Gates Foundation statistics, 85 percent of those who die of malaria are children under the age of five.

Informal language can, however, enliven personal essays, journalism, and similar kinds of semiformal writing:

Even little kids like some tracks by the band Vogon Soup.