Understanding linux kernel absolute file name
 

Dears,

I really couldnt understand what is the linux kernel file name means , i mean every single part of it , like the below (its my linux box kernel)

Linux RHCL1 2.6.18-53.el5 #1 SMP Wed Oct 10 16:34:02 EDT 2007 i686 athlon i386 GNU/Linux

Q1 - What does the numbers means?
Q2 - what is the SMP?
Q3 - what is the date mentioned?
Q4 - What should i do if i need to update my kernel?

Thanks

man uname