ABSTRACT
We are familiar with the notion of convergence of sequences of numbers (real or complex) and its useful role in analysis. This notion can also be introduced in topological spaces. But, as we will see, the basic theorems describing the topology of spaces and continuity of functions in terms of the convergence of sequences fail in the general setting. This problem can be dealt with by means of the \nets" or the \lters" which will be treated in the next two sections.
