Tech Terms and Features Explained

What is eSIM and how does it work?

An eSIM is a digital SIM card built into your phone. Instead of inserting a physical plastic card, you activate a carrier plan by scanning a QR code or entering an activation code. According to Apple’s eSIM support page, most iPhones since the iPhone XS support eSIM, and iPhone 14 and later models sold in the United States are eSIM-only with no physical SIM tray.

The practical benefit is carrying two phone numbers on one device. Travelers can add a local data plan without swapping SIM cards. Most major carriers including AT&T, T-Mobile, and Verizon support eSIM activation. Android phones from Samsung, Google, and others have supported eSIM since around 2020, though support varies by carrier and region.

What is RCS messaging and why does it matter?

RCS (Rich Communication Services) is the replacement for SMS text messaging. It adds read receipts, typing indicators, higher-quality photo sharing, and group chat features that work natively in your phone’s messaging app. According to Google’s RCS information page, RCS is available on Android through Google Messages and on iPhone starting with iOS 18.

Apple added RCS support in iOS 18, released in late 2024. This means Android-to-iPhone messages now support higher resolution media and read receipts through the default Messages app. Messages between iPhone users still use iMessage. RCS does not include end-to-end encryption by default in cross-platform conversations, though Google has pushed for the GSMA standard to include it.

What does end-to-end encryption actually mean?

End-to-end encryption (E2EE) means only the sender and recipient can read a message. The service provider that transmits the message cannot decrypt it, even if compelled by a court order. According to Signal’s documentation, the Signal Protocol powers E2EE in Signal, WhatsApp, and Google Messages (when both users are on RCS).

Not every app that claims encryption is end-to-end encrypted by default. Telegram, for example, encrypts messages in transit but stores standard chats on its servers in readable form. Only Telegram’s Secret Chats feature uses E2EE. WhatsApp and Signal encrypt all messages end-to-end by default. If privacy is a deciding factor, check whether E2EE is on by default or requires manual activation.

What is a VPN and do you actually need one?

A VPN (Virtual Private Network) encrypts your internet traffic and routes it through a server in another location. This prevents your internet provider from seeing which websites you visit and can make your traffic appear to come from a different country.

Most people do not need a VPN for everyday browsing. HTTPS already encrypts the connection between your browser and the website you are visiting. A VPN adds value in three specific situations: using public Wi-Fi where traffic interception is possible, bypassing geographic content restrictions for streaming services, and preventing your ISP from logging your browsing activity. The honest assessment: a VPN is a useful tool for specific situations, not a security necessity for everyone. According to ProtonVPN’s analysis, the primary benefit for most users is ISP privacy, not protection from hackers.

What are passkeys and how are they different from passwords?

Passkeys replace passwords with cryptographic key pairs tied to your device. When you create a passkey for a website, your phone generates a private key stored locally and a public key sent to the website. Login happens by verifying your identity with your fingerprint, face scan, or device PIN. No password is transmitted or stored on the server.

According to the FIDO Alliance passkey documentation, passkeys cannot be phished because there is no secret to type or intercept. Google, Apple, and Microsoft all support passkeys across their platforms. The adoption is still early, but major services including Google accounts, PayPal, and Best Buy accept passkey login. Passkeys sync across your devices through iCloud Keychain on Apple or Google Password Manager on Android.

What is Wi-Fi 7 and which devices support it?

Wi-Fi 7 (802.11be) is the latest wireless standard, offering peak speeds up to 46 Gbps, lower latency, and the ability to use multiple frequency bands simultaneously. According to the Wi-Fi Alliance certification page, Wi-Fi 7 devices began shipping in early 2024.

In practice, you will not see 46 Gbps. Real-world speeds depend on your internet plan, router quality, and interference. The meaningful improvement is latency reduction and stability when multiple devices share the network. Samsung Galaxy S24, Google Pixel 8 Pro, and several laptops from 2024 onward include Wi-Fi 7 radios. You need both a Wi-Fi 7 router and a compatible device to benefit. If your current Wi-Fi works well, there is no urgent reason to upgrade.

What is cloud storage and how much free space do you get?

Cloud storage saves your files on remote servers accessible from any device with an internet connection. The major providers offer free tiers with different limits. According to their respective pricing pages, Google Drive provides 15GB free (shared across Gmail, Drive, and Photos), iCloud provides 5GB free, and Microsoft OneDrive provides 5GB free.

Dropbox’s free plan offers 2GB, which is functionally useless for anything beyond a few documents. Google’s 15GB is the most practical free tier because it covers email attachments and photo backup. For most phone users, the decision comes down to platform: iPhone users default to iCloud, Android users default to Google Drive. Both charge roughly /month for 100GB when the free tier fills up.

How we write these explainers

Each term on this page is explained using only official documentation and published specifications. We avoid analogies that oversimplify and focus on what the technology actually does, what it replaces, and whether it affects your daily device use. Our research methodology page describes the full process.