Usually we have different programs installed to perform same task.
Now you can choose a program as a default program for particular task.
Now we will see how to do this.
You can see lots of windows tricks in Windows tricks section.
To set a program as default, go to Control Panel.
Then go to Programs.
Then go to Default Programs .
Next click on Set your default programs.
Now choose a program from the left pan which you want to set as default.
For example I choose Chrome to set is as my default browser.
And then Click on Set this program as default.
It is done and Google chrome is set as default browser.
Choose which file type a selected program should open as default.
The below example will describe it all.
Say I like to set my VLC player will be default player for some particular media format.
To do perform previously described steps and click on Choose default for this program.
There a list of file types will open and select for those types you want VLC as default.
Then Save the changes.
Now VLC will be default player for the selected file types.