Mac OS X's Software Update -- a Rundown

 Apple issues update for Mac OS X and some of its applications (such as iLife and Safari) using a function in the operating system called Software Update. To run Software Update, click on the Apple () menu and select Software Update. It may take a minute or two for this feature to perform longer if updates are available for download and installation. (You may need to restart your Mac, so it's a good idea to run Software Update if you do nothing else. You have the option to cancel if you are in the middle of something.)

Standard Software automatically on a weekly basis. You can change the frequency, or even eliminate, the Software Update preferences (for both Lion and Snow Leopard) can be found in System Preferences, Software Update can be found in the System section. Here is how you use the software to your liking.

Step 1: What is the frequency
When the Software Update system preference opens the Scheduled Check section of the settings. Here you can manually run an update check by clicking Check Now button.

Below is where you set the frequency for automatic Software Update. In Leo, whose settings are dimmed, click the padlock in the bottom left corner and you will see a prompt where you enter your password.

If you want Software Update automatically, click on Check for updates checkbox. In the pop-up menu, select daily, weekly or monthly. Remember, you can always run the software manually if you wish, either by  -> Software Update or by clicking the Check Now button in the Software Update system preference. If you do not want Software Update to run automatically, check this box.

Step 2: Automatic settings
When you select Check for updates in the box underneath an option available. This setting allows your Mac to automatically download updates, or updates are available.

If you decide not to activate this feature, but still works automatically check for updates, then Software Update tells you updates are available and you will be able to list the updates seen to set the date later or to go ahead and install the updates.

Step 3: The software installed

In the Software Update system preference, there's a second part, called the software installed. This gives a list of the software is updated via Software update for your reference. There are no options in this section for you to change.

When you're done, lock the padlock at the bottom left, click it and close the settings window.

Other updates
If you have purchased a third-party application in Mac App Store, you use the Mac App Store to download updates. Other apps you can check for updates via the software itself or through preferences app, or through a menu selection.