Contents of /dev/

[Fergus Daly]

Until recently my Cygwin installation (which is of considerable size though far from complete)
consisted entirely of directories (here about 3300), files (49000), links (2300) and just 1 socket.
Now under /dev/ I find 
3 directories
0 files
4 links
12 type b being block (buffered) special
17 type c being character (unbuffered) special
I don't think I've installed anything new for ages so these have probably arrived with an update.
For me the last two types are an entirely new animal. Is it easy to explain what they are and (only
secondly, out of interest) whether anybody else is experiencing this for the first time?