WordPress automatically places a line of text between your <head> tags which states the version you currently have installed. I have read that it is there for statistical reasons which is all fine and dandy, but sometimes showing off which version of WP you are using lets hackers know exactly what vulnerabilities your site has.
For security reasons, I suggest removing the generator, and doing so only takes one line of code.
The WordPress generator line looks like this:
<meta name="generator" content="WordPress 2.8" />
To get rid of it, open up your functions.php file. It is located in your theme’s folder. If there is no functions.php file, create one and just add the following code.
Be sure to place it between <?php><?> tags.