A Page is the area that occupies the entire viewport of the screen during its current state. It organizes information while considering:

Mobile Display Elements

Message Display Characteristics

Legibility: Refers to the ease with which the elements (letters, numbers, symbols, etc.) can be detected and discriminated from one another.

Conspicuity: In addition to involving legibility, it also implies other display characteristics. It is nicely summed up by the notion of signal/noise ratio–the ease with which a given piece of information is detectable in the presence of other competing information.