How to make Pages in Posts for WordPress
When writing long posts in your blog I would suggest using pages to break them up. If the post you are writing is longer then the template it can leave alot of white space in your side bars and throw off the entire balance of the site template. Using the quick tag of “Next_Page” (follow the link to the codex) will put the page tag on the bottom of that post to indicate the next available page numbers.
You will find that this helps keep your blog clean and uniform.
Password Protected Posts in WordPress
Wordpress Codex defines them as: To keep this particular post private so that only those with the password can read it, enter a password here. Be sure and write it down somewhere safe.
It seems to be a simple feature, and may come in handy in some cases; but I would not use it for critical information.