For using an external monitor you will need the appropriate output on your laptop. In most cases this is either DVI-D preferably, or the older VGA out port. DVI-D is preferable since it allows for a purely digital signal as opposed to VGA, but should you need to connect to a VGA-input only monitor/TV it is completely backwards compatible. Note that having a VGA out does not mean it can be converted to DVI-D.
Also most televisions today come with HDMI, which again is just another consumer format typically used with televisions because it not only transfers a digital video signal but a digital audio one in the same cable as well. Plus it's a much smaller interface to boot. DVI-D can be easily converted to HDMI, but since DVI only transfers a video signal, you won't be able to transmit audio from a laptop to a television using a DVI-D to HDMI cable.
Assuming you have a gaming laptop, you should hopefully have a DVI-D output, which is typically white and bigger than a VGA one, and should be all set for any current video output needs. Again the exception being the ability to drive display which support a resolution of something greater than 1920 x 1200, for which one would need a dual link DVI output (a rare feature in laptops).
So there's a long winded answer for you. For the most part you're all set and don't need anything else assuming you have a relatively new gaming laptop.