According to Wikpedia, hardscapes, in the practice of landscaping, refer to paved areas–like streets & sidewalks, large business complexes & housing developments, and other industrial areas where the upper soil profile is no longer exposed. The term is especially used in heavily urbanized or suburban areas with little bare soil.
Typical small-scale hardscaping examples include patios and sidewalks. Retaining walls are often used to create boundaries between hardscapes and earth landscaping features, or softscapes. From an urban planning perspective, hardscapes can include very large features, such as paved roads and traffic circles or traffic islands. Most artificial water features are technically hardscapes because they require a barrier to retain the water, instead of letting it drain into the surrounding soil.
From an aesthetic perspective, hardscaping allows workers to erect landscaping features that would otherwise be impossible due to soil erosion, or that compensate for large amounts of human traffic that would cause wear on bare earth or grass. For example, sheer vertical features are possible.