what's sudo dpkg --configure -a?

[LinuxIsOne]

Hello,

I have installed Ubuntu 10.04 LTS and when I was installing 'Ubuntu
restricted extras', it got stuck in the middle. I restarted and again
the Software Center was saying to first repair the previous
installation before installing anything new.... So finally after
searching I run this command:

sudo dpkg --configure -a

And after entering password, it ran around 15-20 mins....and the
starting lines were like this:

Setting up ubuntu-restricted-extras (39) ...
Setting up ttf-mscorefonts-installer (3.2ubuntu0.1) ...

and then a long-long-long output...What it was doing...? Is it okay?

Thanks.