Unless you really have to, WordPress site migration is your last resort. This process is not easy. In fact, without additional tools to migrate your site to another URL, this is probably one of the most technical jobs an adminstrator can perform.
Thankfully there are some great and free plugins that will do WordPress site migration for you. All-in-One WP Migration for example, is one of those plugins that made migration task a breeze. With this, or similar plugins around, you generally don’t need to do manual site migrations unless you really have to.
But it’s still good to know a thing or two about it.
WPShout.com explains what WordPress site migration means: http://wpshout.com/commonsense-wordpress-site-migration/