ISSN for short, the International Standard Serial Number is the identifier accepted for periodicals (which are works published regularly on some type of schedule; GIIW!, for example, promises to publish their writer's newsletter sporadically, "never knowing" when you'll get your newsletter nor how often).
We've all seen the ISSN as a line of numbers or a barcode for decades-the letters "ISSN" are followed by two groups of four numbers (and/or possibly an X*) divided by a hyphen. This is commonplace enough you might not notice it.
However unremarkable the ISSN has become, for the business owner/newsletter writer, it's use can be quite remarkable:
By obtaining and using an ISSN, you automatically lend an air of credibility to yourself and your newsletter in the way that a business card, once-upon-a-time, gave a buyer confidence in the card-giver and his gimmick. Sure it doesn't promise quality or usefulness--certainly there's no "buyer beware"--but that's beside the point: people believe in it and that alone is worth untold sums.
ISSNs have other relatively "just okay" points, such as electronic archiving and cataloging, which are especially useful in libraries, keeping your publication within public reach. Furthermore, while I've never personally seen this happen, it's been said newsletter old files can easily be updated across the board thanks to standard identification.
Apply for an ISSN for serial publications because having a leg up on competition from the get-go far outweighs the time it takes to fill out and send in the application.
Share in our comments what is your newsletter and where can we find it? Have you obtained an ISSN? What caused you to make this decision? If you do not have an ISSN, are you now going to apply for one?
Where to Go:
What you fill out depends which country you are in or publishing in, be sure to read all the information that pertains to you before filling in the application found at ISSN.org