Preposition stranding

A preposition is stranded if it doesn't move along with its complement.

Example
in (i)a the preposition with is stranded.

(i) a Who did you speak with? b With who did you speak?

The example in (i)b shows the case where the preposition moves along with the wh-word (see Pied piping). Preposition-stranding is restricted: it cannot be applied to all prepositions, and it is impossible in at least French and Italian.

Links
Utrecht Lexicon of Linguistics