What happens when you do kill a program in linux ?

I had two simple questions:

• 
  q1: how to you stop(kill) a program in linux ?
  
• 
  a1: i use the kill command as in

  kill 99 or kill -9 99

• 
  q2: ok ... so what does it really happens ?
  
• 
  a2: himm ... good question - well i send a signal to the program via a system call and then the kernel will take care of the rest ... as in will kill the program
  q2.1: himm so how does it kill it ?! what does it really happens
  a2.1: you know what let me think about it ... yeah i didn't look into this - well let me trace it and will find out ...
  

  shell$ bash &
  [2] 29120
  shell$ strace kill 29120
  execve("/usr/bin/kill", ["kill", "29120"], [/* 23 vars */]) = 0
  brk(0)                                  = 0x8849000
  access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
  open("/etc/ld.so.cache", O_RDONLY)      = 3
  fstat64(3, {st_mode=S_IFREG|0644, st_size=24036, ...}) = 0
  mmap2(NULL, 24036, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7f1e000
  close(3)                                = 0
  open("/lib/libc.so.6", O_RDONLY)        = 3
  read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340\17K\0004\0\0\0"..., 512) = 512
  fstat64(3, {st_mode=S_IFREG|0755, st_size=1611564, ...}) = 0
  mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f1d000
  mmap2(0x49b000, 1332676, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x110000
  mprotect(0x24f000, 4096, PROT_NONE)     = 0
  mmap2(0x250000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13f) = 0x250000
  mmap2(0x253000, 9668, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x253000
  close(3)                                = 0
  mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f1c000
  set_thread_area({entry_number:-1 -> 6, base_addr:0xb7f1c6c0, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
  mprotect(0x250000, 8192, PROT_READ)     = 0
  mprotect(0x497000, 4096, PROT_READ)     = 0
  munmap(0xb7f1e000, 24036)               = 0
  brk(0)                                  = 0x8849000
  brk(0x886a000)                          = 0x886a000
  kill(29120, SIGTERM)                    = 0
  exit_group(0)                           = ?
  
  

  from the second line at the bottom i can see that a kill(PID, SIGTERM) was sent to the process and the return code is 0 (meaning success), but does it really happens into the kernel ?! - it will take me a lot more to explain but I found a good article about it at http://www.ibm.com/developerworks/library/l-linux-process-management/