Map Key Download

I am very new to OpenStreetMap and I find this confusing. I have looked at OpenStreetMap in two browsers. On the right (not left) of the map there are various buttons on a black background. One of these is a lower case i which when you mouse-over says "Map Key".

It would be good to have a higher quality version of this key, because in my browsers (old Firefox and modern Opera) I can only distinguish the colours of the area features ("Forest" down to "School and University") - the textures which I can see in the map are not visible in the key.

Well yes and no :-)

OpenStreetMap is a geo-data project and so there is no one single map and associated key for the features,

If you are referring to a map key for the "standard" rendering of the data, there is a link on the left hand side of the page labled "Map key" that provides what you want. Outside of that it really depends on the provider of the online map if there is a key available or not.

If your question is more about all the possible features that can be included in OSM (and displayed if somebody creates a map that shows them), your best place to look is: http://wiki.openstreetmap.org/wiki/Map_Features

However be aware that the list is by no means complete. OSM allows a great freedom in tagging real world objects and a great many schemes are in use that are not properly documented.

Is it the Map Key, that can be found in the left column of http://www.openstreetmap.org/, you are looking for?

Or do you want a list and explanation of all 42,300 keys currently in use? Well... far from all of them are documented, but the Map Features wiki page is a good starting point.