How to hide folders or files in windows and linux ?

In Windows/

Here you have two methods.

1. "hidden" attibute
Right click on the file or folder. Go to "Properties". In the "General" tab, you can tick mark the "Hidden" in the "Attributes". And the folder or file will be hidden from the users. Also Go to My computer-> Tools(In windows 7, press ALT)->Folder Options. There change the option to "Do not show hidden files".
2. Command line
This method is better than above. Take command line prompt in windows in administrator mode. then locate your folder , say i want to hide the D:\Pictures\family folder. for that type following command and press ENTER.
attrib +s +h D:\Pictures\family
If you want to make it visible again , type the following
attrib -s -h D:\Pictures\family

In (Ubuntu) linux

In ubuntu, any file or folder name starting with a fullstop/period "." will be hidden by default. For example the folder .music will be hidden. So rename your file or folder such that add a fullstop at the starting. Done !