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The 
TTY
, 
STAT
, and 
TIME
 fields are new; we didn't see those when we ran 
ps
 by itself. 
The 
STAT
 field gives
 us the status code of the process, which refers to which state the 
process is currently in. The state can be uninterruptible sleep (
D
), defunct (
Z
), stopped 
(
T
), interruptible sleep (
S
), and in the run queue (
R
). There is also paging (
W
), but that 
is not used anymore, so there's no need to cover it. Uninterruptible sleep is a state in 
which a process is generally waiting on input and cannot handle additional signals 
(we'll briefly talk about signals later on in this chapter). A defunct process (also referred 
to as a zombie process) has, to all intents and purposes, finished its job but is waiting on 
the parent to perform cleanup. Defunct processes aren't actually running, but remain in 
the process list and should normally close on their own. If such a process remains in the 
list indefinitely and doesn't close, it can be a candidate for the 
kill
 command, which 
we will discuss later. A stopped process is generally a process that has been sent to the 
background, which will be discussed in the next section. Interruptible sleep means that 
the program is idle: it's waiting for input in order to awaken.
The 
TTY
 column tells us which TTY the process is attached to. A TTY refers to a