Mac OS X has a number of features that can reduce your Mac's use of electricity — extending battery life for laptops and reducing power costs for everyone. Some of these settings can also affect your Mac's security in subtle ways.
To adjust your Energy Saver settings, choose System Preferences and then click Energy Saver. What you see there depends on whether you're running Leopard or Snow Leopard and whether you're using a laptop or desktop Mac — and for laptops, which particular model you have. Desktop Macs, naturally, run only on AC power, whereas laptops have separate settings for running on battery or when their power adapter is plugged in. In addition, on some laptops, Leopard divides the settings for all computers into two groups — a Sleep tab and an Options tab — whereas Snow Leopard's Energy Saver preference pane has just one view (except for laptops, which require separate tabs for battery and AC power). Figures 4.13 and 4.14 show two of the possible variants. You may need to click a Show Details button show the Sleep and Options tabs.