A generalization of a sequence. Whilst the topology of a metric space can be characterized by sequences, this is not generally true in topological spaces. A net (x_λ‎) in a topological space X consists of points indexed by a set (Λ‎,≤) with the properties (i) λ‎≤λ‎ for all λ‎ (ii) if λ‎₁≤λ‎₂ and λ‎₂≤λ‎₃, then λ‎₁≤λ‎₃ (ii) for any λ‎₁,λ‎₂ there exists λ‎₃ such that λ‎₁≤λ‎₃ and λ‎₂≤λ‎₃. A net (x_λ‎) then converges to x if for any open set U containing x, there exists μ‎ such that whenever μ‎≤λ‎, then x_λ‎ is in U. Then, for example, x is in the closure of a set A if and only there is a net in A which converges to x.

Remaining after all deductions have been made. For example, the net income from the sale of a house will be the sale price less fees paid to lawyers, estate agents, etc. involved in the sale. Compare with GROSS.