I
- i.e.
- (that is) Always use periods and make it lowercase. It always has a comma after it.
- initials
- F. J. Smith (use space) but F.J.S. (no space with initials only)
- instructor
- Capitalize as a formal title before a name. Instructor John Smith is teaching that class. Lowercase in all other cases: John Doe is the instructor of Culinary Arts.
- internet
- Not capitalized.