Background Apps on smartphones and tablets.

It's probably more accurate, if less sensational, to say that, compared with leaving them alone, closing unused background apps doesn't improve battery life and may increase battery drain, depending on which apps and the individual user's pattern of phone usage. The reason is to do with the way multitasking operating systems (e.g. Android or iOS) work. On both of these, algorithms run memory management. They'll close apps that need to be closed, typically ones that have been dormant for a while or are using more power or memory than they should. And they're very good at knowing when you're going to need data, or want a refresh, or open an app again. Apps that are already in memory open quickly, rather than having to fully start again; it's like waking your computer from sleep rather than rebooting it completely. You're far, far better off letting the system work for you rather than forcing it to re-open and re-start everything every time. Battery questions aside, it makes your phone slower and less coherent.

A similar situation exists with a multitasking computer operating system such as Windows, Linux, or macOS. Naive users may learn to find out how much memory (RAM) the system is using, and grow alarmed when they see that the system seems to be using most, or all, of the installed RAM. They think they are "running out of memory", and may fall prey to unscrupulous sellers of "RAM booster" software apps that claim to shut down unused background apps or clear "unused" memory. The fact is that the operating system is designed to use any spare memory to store frequently used data, or to buffer disk operations, and like a phone OS, is able to promptly allocate some of the spare memory when an application needs it. meddling rarely does any good, and may impact performance negatively.