Microgramma (also known as
Eurostile if you included lower case) was a
sans serif font designed by
Aldo Novarese in 1952. It became popular for use with technical illustrations in the '60s. Early typesetters (like the AM
Varityper) incorporated it. Many people today would instantly recognize it as "oh, that's the
Star Trek font!' (Or more accurately they'd recognize Microgramma
Bold Extended as the Star Trek font.)
The font was made popular when it appeared as the
body font in Franz Joseph's
The Star Fleet Technical Manual. Although many in the typesetting community found it dated looking by the '70s, it looked quite futuristic to your average
Trekkie.
The font got incorporated into various displays in six of the Star Trek movies and is used in the
United Federation of Planets seal. It's also popular with various Star Trek publications, like
Mr. Scott's Guide to the Enterprise, as well as fan works.
I believe the TV shows have broken away from Microgramma and had their own custom fonts. The original series used a font standard in the American military at the time called
Machine.