Yes, but they're often used for "mere" interpolation, especially in languages where, rightly or wrongly, string concatenation is believed to be inefficient. I personally do this nine times out of ten, if only out of habit.

For my part, I've never personally liked the use of "+", in particular, to denote concatenation, for the (admittedly silly) reason that string concatenation is not commutative. If nothing else, it's a bit of a slippery slope to even more dubious operator overloads, though not nearly so much as C++'s bloody I/O "operators"!

It's not uncommon to use + for groups even if they're not abelian, esp. with near-rings.

This takes all its importance with duck-typing, as syntactic sugar of binary operators will be translated to a method call, e.g in Ruby a + b becomes a.+(b) [0]. while in Python it's a.__add__(b) [1]. The result might be commutative, but the call and evaluation order certainly is not.

[0] http://ruby-doc.org/core-1.9.3/Fixnum.html#method-i-2B [1] http://docs.python.org/reference/datamodel.html#object.__add...