What's the difference between "da," "dort," and "hier"?
hier: "Here," close to the speaker.
da: "There," generally referring to a place not far from the speaker, or a place previously mentioned. Can also mean "here" informally. Very versatile.
dort: "There," "over there," a place further away from the speaker.
Example
*Komm hierher!* (Come here!)
Mein Buch ist da. (My book is there/here - can be ambiguous, depends on context)
Der Baum steht dort drüben. (The tree is standing over there.)