Not running your Mac as an admin?

I've been told that when I get my Macbook I shouldn't run it as an admin. I have some questions about this.

1. Why shouldn't I run my Macbook as an admin?

2. What is it called if I'm not running it as an admin? Running it as a regular user?

3. How do I not run my Macbook as an admin?

4. Will I be able to use software update if I'm not running it as an admin?

1. Security, and to avoid making mistakes like deleting system files - just like Windows, Linux or any other OS
2. It's called running as a regular user.
3. You don't have to do anything to not run as admin
4. Yes.

Whatever user you created when you first booted your system likely has administration privileges sufficient for 99.999% of the tasks you need to perform. That includes installing software. You have to enable certain things to have true "root user" access. If you look in System Preferences > Accounts and select your user, you should see there is a check box that is labeled "Allow user to administer this computer".

When you first set up a new Mac, you'll set up a single Administrator account, usually with your name. This account has the ability to change system settings, install system software, and to install application software that is available to other users. Mac OS X 10.6 Help: Using an administrator name and password

Having that sort of power makes you dangerous. If a normal user does something foolish, he or she may mess up that user account; if an administrator does something foolish, he or she may mess up the entire system. By not running as the administrator all the time, you force yourself to stop and think before you make a major decision.

Assuming that you have only the original administrator account that you created when you first started, the easiest way to switch over is to
1. Open System Preferences and create a new Administrator account, by checking the box XJ-linux mentioned. (Don't call it "administrator" or "admin" or anything like that; use a name not likely to be guessed.)
2. Log into the new Administrator account
3. From the Administrator account, un-check the Administrator box for your old account. This will turn it back into a standard account.