We use the verb "SAPERE" to say that we know things in general, such as languages, and that we know how to do things (reading, writing, etc.). We use the verb "CONOSCERE" when we met someone for the first time, and to indicate that we are familiar with a place, situation, and so on (for example : "we know a nice B&B in Milano" -----> "Noi conosciamo un bel B&B a Milano")

The verb conoscere is used when you want to say that you are familiar with something or someone. You use it almost always on people, places and objects. It is when you have seen/met/was introduced to something or someone in the past and it is no longer something new to you (as I said, you are familiar with it). Sapere is used when talking about knowing something as a fact (I know the sky are blue), or as a skill (I know how to speak italian), but not in a sense that you are familiar with something/someone. All the languages I know and learn differentiate between these two verbs. Interestingly enough, English doesn't do that. :)