The technologies involved in communication tend to be complex. You certainly don't need to understand them for your ICT course. However, there are aspects of digital communications that you needs to be aware of. These relate primarily to the two types of network and the ways of connecting to the internet.
Archaeans include inhabitants of some of the most extreme environments on the planet. Some live near rift vents in the deep sea at temperatures well over 100 degrees Centigrade. Others live in hot springs (such as the ones pictured above), or in extremely alkaline or acid waters.
Another type of archaebacteria are halophiles. Just as thermophiles thrive in extremely hot environments, halophiles thrive in extremely salty environments. They make their home in water and soil, as long as there is a very high amount of salt.