The latest iPhone and Android devices are all outfitted with something new called eSIM, which replaces the tiny, physical SIM cards of yesteryear. This is a good thing.

As your smartphone’s built-in identification card, a SIM enables you to make calls, send texts and browse the internet on a cellular network. eSIM, which is built into your device, picks up where those the physical cards left off, keeping your phone more secure while making it easier than ever to upgrade.

Here’s what you need to know.

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