
 15.1 Infinite Series and Convergence (Site not responding. Last check: 20071011) 
  If we have an infinite sequence, we define it to be convergent if, for any positive criterion, q, however small, beyond some term, say the n(q)th, all of the terms are within q of some number, z which we call the limit of the sequence. 
  Then convergence of the series is defined to be the same as the convergence of that sequence of partial sums. 
  When a series is absolutely convergent, you can rearrange its terms, differentiate it term by term if terms contain a variable, and perform other manipulations, which may not work for merely convergent series. 
 wwwmath.mit.edu /~djk/calculus_beginners/chapter15/section01.html (292 words) 
