Like the OS on a desktop or laptop, you can update or patch the OS on mobile devices. Updates add functionality or increase performance. Patches can fix security problems or issues with hardware and software that do not work properly.
Because there are so many different Android mobile devices, updates and patches are not released as one package for all devices. Sometimes a new version of Android cannot install on older devices where the hardware does not meet the minimum specifications. These devices might receive patches to fix known issues, but not receive OS upgrades.
Android updates and patches use an automated process for delivery. When a carrier or manufacturer has an update for a device, it shows up as a notification on the device that an update is ready. Touch the update to begin the download and installation process.
iOS updates also use an automated process for delivery, and devices that do not meet the hardware requirements are also excluded. To check for updates to iOS, connect the device to iTunes. A notice to download opens if updates are available. To manually check for updates, click the Check for Update button in the iTunes Summary pane.