In certain cases, two or more consecutive characters are joined to a single glyph. This is called a ligature. LaTeX commonly does it for ff, fi, fl, ffi, ffl, and more, depending on the font. That's because font makers designed specific glyphs for certain character combinations.
While it looks fine in print and on screen, there is a caveat—if you copy text from the produced PDF file into another document, such as to a text document or a Word file, the ligatures may appear broken.
Another problem is searching for words containing ligatures in PDF files, which can simply fail as the ligature "ff" is not equivalent to the letter combination "ff".
We will now fix that.
We stick to the commonly used pdfLaTeX. There are several possible ways to fix it. The first way is this:
Insert the
glyphtounicode.tex
file into your document's preamble:\input{glyphtounicode}
In the next line, activate the required pdfTeX feature:
\pdfgentounicode=1