debian has precompiled packages of binaries and libraries that can
very easily be installed via the command line (or GUI) using 
Advanced Packaging Tool (APT)

apt-cache search ssh        //to find packages with the name ssh
apt-cache show ssh          //to show the details about a specific package
apt-cache showpkg ssh       //to show more general info about a package
apt-cache depends ssh       //to show the package dependencies


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dpkg -S stdio.h             //find a package that contains a specific file
dpkg -l | grep mozilla      //lists all packages but only return "grep mozilla"

dpkg --get-selections > installed-software.txt

dpkg -i package.deb         //installs a given package
dpkg -i *deb            //installs all deb files in a directory
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apt-get download apache2.2-common       //to download first, then install

apt-get install apache2                 //to download & install a package

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apt-cache dump              //shows all installed packages
apt-get purge apache2-common            //to seriously remove a package
apt-get autoremove                      //to try to clean up orphaned packages?

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apt-get clean

the /var/cache/apt/archive folder keeps a copy of the downloaded .deb 
files before installing them (e.g. to the /usr folder)

you can run apt-get clean to remove these extra files (though you'll need
an internet connection to reinstall all of those .deb's)
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apt get does not work (or seems to time out)

sudo nano /etc/apt/sources.list

change the gb.archive.ubuntu.com to a us.archive... or you get the idea :)