Permalinks are the URLs that are used to navigate from page to page on your website. Visitors rely on these to return to your content either through bookmarks or the URLs that search engines capture when they index your pages.
A URL with a meaningful name makes it easier to locate your content as people search for key words and phrases and not page numbers. WordPress offers a variety of options for its permalink structure. These include page numbers (default), Day and Name, Month and Name, numeric, post name and custom.
I use post names on all my websites as this is both simple and functional; and most of my content and articles are enduring i.e. no used by date.
Here are some of the things to watch out for when changing your permalinks if you encounter broken links:
mod_rewrite?