The Windows Task Manager is a utility that allows you to check the performance of your PC. It is a little technical to explain how it can help you but it's worth perseving to learn about it. Below is a wikipedia entry for the Task Manager and also a youtube video that runs for around ten minutes.
Our own written entry on the Windows Task Manager follow this link:
If you prefer to read how 'stuff' works this wikipedia page will tell you all about Bookmarks; what they are, how they work and why they are incredibly useful.
IMPORTANT NOTE: It doesn't matter what type of computer, tablet, smartphone you use. Wikipedia works in the similar way across ALL operating systems.