Limit of a Function

We now move from the idea of a sequence — a list of numbers approaching a target — to the behaviour of a function as its input gets arbitrarily close to some point. The central question is: what value does $f(x)$ tend toward as $x$ draws nearer and nearer to a given number $a$, even if $f(a)$ itself is not defined? This intuitive notion of "approaching" is the heart of the li …