The four kinds
Operating system security patches are small, frequent and the ones that matter. Feature upgrades are the big annual releases with a new name and a rearranged settings page. App updates arrive through the app store or the program itself. Firmware is the software inside hardware, including your router, your television, your doorbell camera and your printer, and it is the kind most people never update at all.
Why the clock matters
When a company publishes a security patch, it also announces to the world that the flaw exists. Attackers compare the old and new versions, work out what was fixed, and build an attack for everybody who has not yet updated, often within days. That is why a security update should go on within about a week, and at once when the release notes say the flaw is already being actively exploited. A major feature upgrade is different. Nothing is lost by waiting two or three weeks for the first round of bug fixes, and you should make a full backup before installing it.
Updates that have not finished
Many updates download quietly and then wait. An operating system patch usually takes effect only after a restart, and a browser update only after the browser is closed and reopened, so a browser left running for three weeks with forty tabs is three weeks out of date. Schedule system updates for overnight, with the machine plugged in, and keep several gigabytes of storage free, since an update with no room to unpack simply fails.
Fake update prompts
A web page that announces that your browser, video player or security software is out of date is malware with a friendly face. Real updates come from only three places: the system's own settings, the official app store, and the program's own menu. Nothing legitimate updates itself through a pop-up on a website, and none of it arrives as an email attachment.
End of the line
Every device stops receiving security updates eventually. Phones are supported for a fixed number of years from the model's release, which ranges from about three to seven depending on the maker, and the date is usually published. Check it before buying a used or discounted older model. A device past its support date still works, but it should not be the one you bank on.
Tip Log in to your router's settings page twice a year and look for a firmware update, or turn on its automatic option if it has one. It is the one computer in the house that every other device trusts.
