Contraction: an + dem = am
This contraction is presented in the "Tips and notes" section on the Basics 2 page of German.
I don't know of this is a mistake, but the definite article "dem" is not described anywhere in this section. The only defitnite articles presented are: "der", "die" and "das" -for the nominative case- and "den", "die" and "das" -for the accusative case-. What am I missing here? is "dem" a definite article? What is it for?