Essentially, the default format just appends a ?p=index_number to the directory and calls it good. That works, but gives nothing for search engines to hang onto. The search engines especially like to see keywords in the URL. In order to give something for them to chew on, that simple integer has to go.

Upon some googling, I have arrived at this custom format: /%postname%/ . This will use the slug version of the title as the generated URL. Done.