A video call transmits camera footage alongside audio in real time. Using a smartphone's front camera or a computer's webcam together with an internet connection, the participants can see each other while they talk. Zoom, Google Meet, Microsoft Teams, FaceTime, and LINE video calls are all widely used.
A video call rests on the same foundation as ordinary internet telephony: audio and video are converted to digital data, split into small packets, and carried to the other party over an IP network. VoIP (Voice over IP) carries only the audio; a video call adds a codec that compresses the picture (H.264 or VP9, for example) plus machinery that keeps latency down and re-aligns the picture with the sound. Services that run entirely in a browser or app usually rely on the WebRTC standard. On a one-to-one call the two endpoints can exchange data directly, but once three or more people join, and on the large group services in general, the audio and video normally pass through a relay server on the provider's side, which redistributes each stream to the other participants.
Call quality depends on connection speed. The figure you need varies with the service and the picture quality, but as a rough guide, allow for at least 1.5Mbps downstream for a one-to-one video call and 3Mbps or more for a group call. The easy thing to overlook is the upstream (upload) side. Many home plans give far less upload capacity than download, so symptoms such as your own picture breaking up, or the other party reporting that your voice keeps dropping, often come from a shortage of upstream rather than downstream bandwidth. Wi-Fi gives the most stable results, though 4G and 5G connections also deliver ample quality.
The 2020 COVID pandemic drove an explosive rise in video calling. Remote work, online medical consultations, online classes, and visits with distant family all adopted video calls as a substitute when meeting in person was difficult, and the habit stuck.
On the security side, what matters is whether the call is encrypted. Zoom introduced end-to-end encryption (E2EE) in 2020, and FaceTime has used E2EE from the start. E2EE is not always on by default, however: some services require you to switch it on explicitly, and turning it on can disable features such as recording or dial-in from a phone line. If you handle confidential information at work, check both that the service supports E2EE and what it gives up once E2EE is enabled before you settle on it.
Two habits on the user's side are worth building. First, the camera captures your whole background, and a piece of mail or the view out of a window can be enough to narrow down where you live; a background blur, or simply sitting with a wall behind you, takes care of it. Second, be wary of anyone who reaches you by phone or email and then steers you toward a video call or screen sharing. Once you share your screen, your account balance and any one-time password that arrives are visible to them as well. If someone you did not contact asks you to share your screen, decline, end the call, and dial the organisation's official number yourself. Our comparison of LINE calls and ordinary phone calls is also worth a look.