Installing and configuring pantheon greeter
lightdm
is a display manager that handles running X server and login in Linux systems. The flexbility of lightdm allowed it to be used with different greeters (login screen). Though the default is Unity greeter, not every distribution uses it as default. Elementary OS project uses their own fork, named pantheon greeter, which in my opinion is most visually appealing.
Fortunately, you can have it in Ubuntu by installing pantheon-greeter
package.
But setting it as default greeter and configuring it needs some work.
###Setting as default greeter
Open the /etc/lightdm/lightdm.conf
file and Use these lines to set it as default.
Configuring some options
You can change or configure some options of the greeter if you want. The pantheon greeter looks better with elementary theme, so make sure you have it installed. To change some options like the font sizes, gtk themes, icon themes etc use /etc/gtk-3.0/settings.ini
file.
Content of the file should look like this by default
So, if you want to change the font name or icon name, change it there and save. Then reload or restart lightdm to see the effect.
Happy tweaking!