# Spacing between letters (ligature)

I noticed today how the spacing between letters are for fl/fi. Is this good a sign of typography? MWE:

\documentclass{article}
\begin{document}
fluid - Fluid

fish - Fish
\end{document}


• What error do you mean? These just look like the fl/fi ligatures in CM to me. – Joseph Wright Mar 5 '16 at 12:37
• The "f" is overlapping "i" and "l". Try with "Office". Here the first "f" overlap the second one! Do you get the same contraction @JosephWright? – TobiasDK Mar 5 '16 at 12:40
• Office doesn't do ligatures without some setting changes, so the result will of course be different (and wrong in Office). Perhaps compare the 'famous' case in English where a ligature should be suppressed: shelfful - shelf\kern0pt ful – Joseph Wright Mar 5 '16 at 12:44
• Can see that it has nothing to do with the update. Same feature in older documents. Is this the desired graphical result? – TobiasDK Mar 5 '16 at 12:45
• yes all reasonable typesetting systems have always done that for hundreds of years. – David Carlisle Mar 5 '16 at 12:52

This is called a ligature and is a sign of good typography. The standard ligatures for TeX are fi, fl,ffi,ffl, but there's also fj and the old style ligatures stand ct, and some others, depending on the font. They're most easily accessed with fontspec and xelatex. Here is an example, with Latin Modern, erewhon (an extension of Adobe Utopia) and Sabon Next LT Pro (the latter is a commercial font, the former two are in TeX Live and MiKTeX):

\documentclass{article}
\usepackage{fontspec}
\newfontfamily\erewhon{erewhon}[Ligatures=Rare]
\newfontfamily\otherfont{Sabon Next LT Pro}[Ligatures=Rare]

\begin{document}

fluid - Fluid - fjord - baffled - suffix

fish - Fish - special act - fb - fk
\bigskip

\erewhon

fluid - Fluid - fjord - baffled - suffix

fish - Fish - special act - fb - fk
\bigskip

\otherfont

fluid - Fluid - fjord - baffled - suffix

fish - Fish - special act - fb - fk
\vskip1 cm

\end{document}