The Blu-ray Disc -official abbreviation BD- is the optical medium created by Sony at the beginning of 2002 as an evolution of the DVD for high-definition television. It permits a huge storage of data, almost 40 times more than a single-layer DVD-Single Side. Because it's bigger than a USBkey, it's not so easy to lose this kind of E-resource, but careful because the BluRay discs are flimsy ;)
It permits a huge storage of data: I would say: it permits (allows) to store a huge amount of data
single-layer DVD-Single Side: The object is "Side" or "DVD" here?
it's: remember: in formal English writing do not use contraction (but this is not so formal, so it's fine :))
