Is there any simplified OSM data?

Hi I'm new comer of OSM community. I can download the OSM street data, but I wonder if there's any simplified street data or data at small map scales. If there are available, I would like to download "OSM data of small scales" directly. If there're not available, I wonder how I can create that data.

In the OSM.org website, the street maps shown on the screen are map tiles of different map scales, depending on your zoom-in/out levels. I'm curious actually how this map tiles were originally created from OSM data.

Would you point me to some relevant posts or websites? Any advice and comments are welcome. Thank you very much in advance!

Annie