The WordPress team releases regular updates and it’s wise to upgrade your blog every time a new version is launched.
Why? Because if you don’t you leave your blog at the mercy of hackers, infections and other malicious mischief. I know two people who’ve been infected via weaknesses in old versions of WordPress.
As well as security fixes, updated versions include fresh functionality. And it’s easy – as well as free – to upgrade your blog in one click via your WordPress Dashboard. If you haven’t done it before, check the instructions on the WordPress website first.