Keeping the installer on hand
Before proceeding with installation, here’s an important tip: If you run the installer from its default location in the Applications folder, the installation process deletes the installer, presumably to free up the 5.3GB of drive space it occupies. So if, as explained above, you plan to use the installer on other Macs, if you want to create a bootable installer drive, or if you just want to keep the installer on hand, before installing, you should copy the installer to another drive—or at least move it out of the Applications folder.