Activity Monitor is a piece of utility software that is similar to Windows Task Manager where almost all information provided by Windows Task Manager are also displayed. Lets just assume it as a task manager for Mac OS X operating system. Displayed below is the image of Activity Monitor found in Mac OS X 10.9 Mavericks. The interface has been altered quite a lot and we can no longer see pie chart representing the RAM usage in sectors. As I found the pie chart is not really informative, I don't really care about the dismissal of that feature.

Mac OS X Mavericks Activity Monitor new UI
To end a task by forcing it to quit, we can simply select the target process so that it is highlighted in blue and then click on the tiny icon located at the top left corner and confirm the action by clicking 'Quit'. This process is very simple and I'm sure you can understand it.

There is also another alternative to quit an application without using Activity Monitor. The job can be done by opening 'Force Quit Applications'. Just press Command-Option-Escape simultaneously and a pop up window will appear. Just select the desired running application and click on 'Force Quit'. I will explain more on Activity Monitor in the next post.