In order to prevent unnecessary server load, edits should be kept to a minimum. Please experiment in the template's /sandbox or /testcases subpage, or in your own sandbox, and consider discussing your changes on the talk page before applying them.
Editing a template causes all pages that use the template to be re-rendered. If the template is used often, this can put a lot of load on the server since it fills up the job queue.
Inserts a pipe character used in internal links. (Probably) used in other templates to prevent a template being evaluated prematurely.