htmlentities() vs. htmlspecialchars()

Question

What are the differences between htmlspecialchars() and htmlentities(). When should I use one or the other?

Answer 1

You probably want to use some Unicode character encoding, for example UTF-8, and htmlspecialchars. Because there isn't any need to generate "HTML entities" for "all [the] applicable characters" (that is what htmlentities does according to the documentation) if it's already in your character set.