If you are planning to format your hard disk drives or just wanna have a back up of your bookmarks or favourite websites, you should consider save them, specially for those with a large list with sub-folders.

This applies to all browsers: INternet Explorer, Flock, Mozilla Firefox and Google Chrome.
In IE: Click on File > Import and Export. Then Choose Export from your browser and in the next window check "favourites". The same steps in Mozilla can be applied but in the bookmarks menu instead of the "file" menu.

Then you choose the location of the file and it will be saved as an html file. You can save the file and "import" it later to the browser in the same way you exported it.

Another wa to avoid this is by using an online bookmaring website, this way, you favourites are always stored online and you never lose them, you can name them and give them tags and file them under categories.

When using online bookmarking sites, you can choose wether to make your bookmarks private (only you can see them) or you can choose them to be public, this means you share them with other members of the website, you can see if any other people boomarked this page before, you can browse other users' bookmarks by interests and each member can vote for any bookmark, you can make new friends based on common interests, etc.

You don't have to log in into the website each time you wanna bookmark.favourite a page. All bookmarking networks allows you to download a toolbar that is integrated into your browser so that you ca directly bookmark any web page while surfing by clicking on an icon or by te usual way "Ctrl + D".

Some of these websites are:
del.icio.us
Digg
clipmarks
stumbleuopn
propeller