Definition:
For purposes of desktop publishing and typography, an upright tick mark is a mathematical symbol otherwise known as a prime used to denote a division into parts — most notably feet or minutes. Six feet may be noted as 6' while 6° 5′ is read as 6 degrees, 5 minutes (a minute represents a 60th of a degree in geometry). There are other ways that this upright tick mark may be used in math notations as well.
The Wrong Apostrophe
The upright tick mark is often used in place of the curly apostrophe in typewritten material, emails, on the Web, etc. It is a straight, upright or slightly slanted tick mark — in some fonts it may be tapered or shaped like an upside down teardrop. When it is used as an apostrophe (or for single quote marks) in typeset material, it is often considered a sign of amateur or sloppy typography.Also Known As: prime | apostrophe | feet mark | minute mark
