Sometimes when you install a program or create a file, they are stored in "pieces" in different parts of the disk. This is called fragmentation.

Fragmentation occurs because sometimes the operating system cannot assign a continuous space to store a complete file, as a unit they were, storing the file in the gaps thus leading to the division or fragmentation.
These gaps and lack of space may be due to file or programs previously eliminated and who left some of their "pieces".

The fragmentations occurs over time and as you use your computer and may lead to system crashes, PC slowdowns, delayed startups and shutdowns, as well as many other problems.

When the PC tries to open a file must meet all the "pieces" that make up that file and takes some time to do it, for example when you let fall to the ground a cup or a plate, it is divided into pieces, now imagine the time and work that you were going to take to join them all back to the way it was. It is more or less what happens to the computer. You think this is bad, but there's worse.

When you open a file to work on it, either to withdraw or to add things when the time comes to save, it will not come back just to divide us "pieces" as before, will be divided into smaller parts, and so successively.
But are not all bad news, now comes the good part. There are two ways that can reduce the possibility of fragmented files:

• Remove Temporary Swap Files;
• Remove the Internet Temporary Files.

But before the scourge of the fragmentation you can and should use defragment software