In English and in German, there are some verbs that are used extensively with certain prepositions. In English, these are called "phrasal verbs". Adding a preposition to a verb changes the meaning slightly. For example, the verb "to run". By itself, it means to move swiftly using your legs. But we can also "run into" someone. Someone can "run for" something, or we can "run something by" someone. We have changed the original meaning of the verb "run" simply by adding a preposition.
There are many verbs in German as well that are used with a preposition. For example "warten" (to wait). I can simply "wait", but I can also "wait for" something. (warten auf). In German, we added the preposition "auf" to alter the meaning of the original verb slightly.
These prepositions can be combined with “da(r)” if we wish to refer back to the object of the preposition, without repeating it.
Wartest du auf dein Paket? Ja, ich warte darauf.
Are you waiting for your package? Yes, I am waiting for it.
The same way that we can build "da" compounds, we can also build "wo" compounds.
2. "Wo" Compounds.
"Wo" compounds are formed the same way that "da" compounds are formed. They are a combination of the question word "wo", and a preposition. If the preposition begins with a vowel, we simply add an extra "r".
The difference between a "da" and a "wo" compound, however, is that "da" compounds are used in statements, and "wo" compounds can only be used in direct or indirect questions or, in some cases, as a relative pronoun.
Freust du dich auf das Konzert? Ja, ich freue mich darauf. (statement, "da" compound).
Are you looking forward to the concert? Yes, I am looking forward to it.
Worauf freust du dich? -Auf das Konzert. (question, "wo" compound).
What are you looking forward to? - To the concert.
Kannst du mir sagen, worauf du dich freust? (indirect question, "wo"compound)
Can you well me what you are looking forward to?
Like "da" compounds, "wo" compounds are also only used for inanimate objects. And just as "da" compounds, There are some prepositions that cannot be used with “wo”: außer, gegenüber, ohne, & seit. Some directional adverbs, such as hin, her, hinein, can be used with “wo” as well (e.g. wohin, woher).