openstreetmap - Convert OSM File to get addresses using Osm2pgsql

I am working to covert OSM File to get all building's informations in the city.

I am using osm2pgsql package to transform the data. Now I am confused as I have 5 tables :

   - planet_osm_point
   - planet_osm_line
   - planet_osm_roads
   - planet_osm_polygon

I am confused now, how can I get buildings' informations from these tables. What do every table represent ?

Blog