Insert an italic correction, a small space defined by the font
designer for each character, to avoid the character colliding with
whatever follows. When you use
\/, LaTeX takes the correction
from the font metric file, scales it by any scaling that has been
applied to the font, and then inserts that much horizontal space.
Here, were it not for the
\/, the before-character
italic f would hit the after-character roman H
because the italic letter leans far to the right.
If after-character is a period or comma then don’t insert an italic correction since those punctuation symbols have a very small height. However, with semicolons or colons as well as with normal letters, the italic correction can help.
When you use commands such as
change fonts, LaTeX will automatically insert any needed italic
correction (see Font styles).
Roman characters can also have an italic correction. An example is in
There is no concept of italic correction in math mode; spacing is done in a different way.