Often, you will encounter locked doors and passages. The only characters that are capable of opening them are rogues. The locks that you have found, but not yet opened, are marked on the map. However, the level of the locks is not the same. To be able to open the more demanding ones, you need to activate the "Deft Hands, Fine Tools" perk, of the Secrets category. However, some of the locks still won't open. These are going to require a key that you can often find near the locked door.