If you are building your own theme or just a simple pate template you’ve probably noticed that although the WordPress loop responds to the “posts per page” limit that is set in settings >> reading it does not come with any pagination buttons to allow the user to navigate to the next or previous batch of entries.
In order to add those pagination buttons to the WordPress loop you simply need to add a line of code after your loop as in the example below (line 7 in the example):
<?php if (have_posts()) : while (have_posts()) : the_post();
// Whatever you want your loop to do goes here
<?php posts_nav_link(' — ', __('« Previous'), __('Next »')); ?>