Killing a process on a Windows machine

How can I kill processes on a Windows machine? Ctrl + Alt + Del only works for the whole system, but I need it for a single process.

Open task manager, go to the process Tab, highlight the process, hit "end process" button.

For Windows XP, Vista, 7:

Basic options overview:

If you know the name:

taskkill /IM (program).exe

If you know the PID:

taskkill /PID ###

Kill all processes by one user (Quinn in this instance):

taskkill /FI "USERNAME eq Quinn"

Taskkill options:

• /F - force kill with no confirmation
• /IM - by program name
• /PID - by process ID number

• /FI - by filter:

  Filter Name     Valid Operators     Valid Value(s)
  -----------     ---------------     --------------
  
  STATUS          eq ne               RUNNING | NOT RESPONDING
  IMAGENAME       eq ne               Image name
  PID             eq ne gt lt ge le   PID value
  SESSION         eq ne gt lt ge le   Session number
  CPUTIME         eq ne gt lt ge le   CPU time in the format of hh:mm:ss.
  MEMUSAGE        eq ne gt lt ge le   Memory usage in KB
  USERNAME        eq ne               User name in [domain\]user format
  MODULES         eq ne               DLL name
  SERVICES        eq ne               Service name
  WINDOWTITLE     eq ne               Window title
  

Modifiers:

• eq: equals
• ne: not equal
• gt: greater than
• lt: less than
• gt: greater than or equal
• le: less than or equal

Besides the Windows Task Manager already suggested here,
I'll recommend keeping Process Explorer by Mark Russinovich handy.

It is more elegant as described in this How-To-Geek article.

it gives you so much more information than the default task manager, including a tree view of all the processes so you can see which processes launched other processes. You can look at pretty much every piece of data concerning a process, including associated registry key handles, open files, dlls. There’s even a search function.

Also see the Wikipedia page, Process Explorer.
^{I always wonder why Microsoft has not yet replaced the default Task Manager with this yet.}

Note the process ID of the process you wish to kill. From the command line type:

taskkill /PID PROCESS ID HERE

Or use Ctrl + Alt + Del and select it from the list.