New media is only new until something newer comes along, so the definition can never be static. Pencils were new media at one time. Someday there will be media that make smartphones look like pencils. For now, it’s reasonable to say that new media is digital–any content created today is easy to digitize, even if it’s written on paper with a pencil–you can just take a photo of it with your smartphone and it’s digital.
Then it can be easily modified into infinitely many versions using software like PhotoShop. This is the second clear quality of new media, discussed by writers like Manovich.
Then your pencil sketch can be sent anywhere and everywhere on the planet (and beyond) via the web, which is the third quality of new media, ubiquity.
There are other qualities worth discussing, like the tension between new media as art and new media as computer software, and whether or not it even makes any sense to say there is a difference. It seems to be mostly a difference of audience perception, which is essentially a rhetorical quality of communication. This means that what the ancient Greek rhetoricians like Aristotle and Isocrates had to say about human communication still applies to new media. Digital, infinitely variable, ubiquitous rhetoric. The human world is essentially created by humans through rhetoric and digitization, if anything, has verified, multiplied, and magnified this relative and subjective truth that the Greeks discovered a few thousand years ago.
Defining New Media 