I've heard a lot of things about [Friction](http://en.wikipedia.org/wiki/Friction) like friction between solids, liquids and gases. Even practical applications like motion of objects (Like car moving on road), etc. involve friction. But, do we really need to concern about Friction. I mean, Is the presence of friction really important in practical life? I goggled through but, i can't understand the depth of it, as all are saying "This wouldn't happen & That wouldn't happen" without friction...

Answers differentiating presence and absence of friction would be appreciated...