Multiple end-user group levels?

Hello,

I’m brand new to WordPress, and wondered if there is a way to limit access to certain end-users based on who they are?
What I am trying to achieve is that I want the whole world to be able to read the normal blog posts and howto’s on the web, but certain pages about our daughter and the photo album should be restricted to logged in users.
I know we can protect certain pages with a password, but it’s not a realistic solution as such passwords are too easily forgotten. It’s better that each user has her/his own username/password combo and get access to the photo album and private blog posts based on her/his group membership or maybe just the fact that they’re logged in, as opposed to guest visitors.