Wi-Fi: Wi-Fi encompasses any wireless local network that conforms to the IEEE 802.11 standard. And that means what, exactly? It means that if your computer or printer or iOS device and a wireless access point (sometimes referred to as a hotspot) support the standard, they can connect and exchange data. In some instances the interaction may entail moving data between one device and another on the same local network; in others, it may involve connecting to the Internet wirelessly.
The 802.11 standard has appeared in numerous variant forms, including 802.11a, 802.11b, 802.11g, and 802.11n. As the standard's last-letter designations move farther along the alphabet, speeds increase (as does range, in some cases). Wi-Fi can be less secure than an ethernet connection. With ethernet, someone needs to tap physically into a network to intercept data; but with Wi-Fi, the interloper only has to be in the vicinity (and have the means of intercepting and decrypting data, of course).
AirPort: This is Apple's name for its Wi-Fi technology. When people talk about "turning AirPort off," they mean that they're turning off their Mac's Wi-Fi.
Bluetooth: Another wireless data transfer standard, Bluetooth has a shorter range (about 30 feet) than Wi-Fi. Bluetooth is commonly used to connect peripherals such as keyboards, mice, trackpads, headphones, speakers, other nearby computers, and some portable devices to a Mac.
Bonjour: Bonjour is Apple's name for its zero-configuration networking scheme. It consists of a complicated series of technologies that are designed to remove the complication from local networking. If you've ever set up a wireless printer, fired up your Mac, and had your computer offer to connect itself to that printer without your having to run through a bunch of complicated steps, you've benefited from Bonjour.
3G and 4G: 3G and 4G (the G stands for generation) are a wireless scheme that cellular networks—the networks that your mobile phone carrier relies on—use to move information around. 4G is supposed to be faster than 3G, but it isn't always.
In the first place, there are several different flavors of 4G—including HSPA+, WiMax, and LTE. And just because a network is termed 4G doesn't mean that it will be speedier than a fast 3G network. For example, Apple issued an iOS update that caused certain iPhone models to display '4G' in the menu bar when, just hours before, the menu bar read '3G'. The network was no faster, but AT&T had defined its HSPA+ network (versus plain-old HSPA) as 4G, even though that designation promised no speed increase.
Sufficient as it may usually be to refer to the thing that makes your wireless network work as "that blinking box over there," a time will probably come—when you're on the phone talking to a member of your ISP's support team, for instance—when you'll need to know what that box is called and what it seems to be doing. Let's name names.
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