You’ve probably seen references to TCP and UDP when setting up port-forwarding on a router or when configuring firewall software. These two protocols are used for different types of data.

TCP/IP is a suite of protocols used by devices to communicate over the Internet and most local networks. It is named after two of it’s original protocols—the Transmission Control Protocol (TCP) and the Internet Protocol (IP). TCP provides apps a way to deliver (and receive) an ordered and error-checked stream of information packets over the network. The User Datagram Protocol (UDP) is used by apps to deliver a faster stream of information by doing away with error-checking. When configuring some network hardware or software, you may need to know the difference.

What They Have In Common

Both TCP and UDP are protocols used for sending bits of data—known as packets—over the Internet. Both protocols build on top of the IP protocol. In other words, whether you’re sending a packet via TCP or UDP, that packet is sent to an IP address. These packets are treated similarly, as they’re forwarded from your computer to intermediary routers and on to the destination.

TCP and UDP aren’t the only protocols that work on top of IP. However, they are the most widely used.

How TCP Works

TCP is the most commonly used protocol on the Internet.

When you request a web page in your browser, your computer sends TCP packets to the web server’s address, asking it to send the web page back to you. The web server responds by sending a stream of TCP packets, which your web browser stitches together to form the web page. When you click a link, sign in, post a comment, or do anything else, your web browser sends TCP packets to the server and the server sends TCP packets back.

TCP is all about reliability—packets sent with TCP are tracked so no data is lost or corrupted in transit. This is why file downloads don’t become corrupted even if there are network hiccups. Of course, if the recipient is completely offline, your computer will give up and you’ll see an error message saying it can’t communicate with the remote host.

TCP achieves this in two ways. First, it orders packets by numbering them. Second, it error-checks by having the recipient send a response back to the sender saying that it has received the message. If the sender doesn’t get a correct response, it can resend the packets to ensure the recipient receives them correctly.

How UDP Works

The UDP protocol works similarly to TCP, but it throws out all the error-checking stuff. All the back-and-forth communication introduce latency, slowing things down.

When an app uses UDP, packets are just sent to the recipient. The sender doesn’t wait to make sure the recipient received the packet—it just continues sending the next packets. If the recipient misses a few UDP packets here and there, they are just lost—the sender won’t resend them. Losing all this overhead means the devices can communicate more quickly.

UDP is used when speed is desirable and error correction isn’t necessary. For example, UDP is frequently used for live broadcasts and online games.

For example, let’s say you’re watching a live video stream, which are often broadcast using UDP instead of TCP. The server just sends a constant stream of UDP packets to computers watching. If you lose your connection for a few seconds, the video may freeze or get jumpy for a moment and then skip to the current bit of the broadcast. If you experience minor packet-loss, the video or audio may be distorted for a moment as the video continues to play without the missing data.

This works similarly in online games. If you miss some UDP packets, player characters may appear to teleport across the map as you receive the newer UDP packets. There’s no point in requesting the old packets if you missed them, as the game is continuing without you. All that matters is what’s happening right now on the game server—not what happened a few seconds ago. Ditching TCP’s error correction helps speed up the game connection and reduce latency.

So What?

Whether an application uses TCP or UDP is up to its developer, and the choice depends on what an application needs. Most apps need the error-correction and robustness of TCP, but some applications need the speed and reduced overhead of UDP.

Unless you’re a network administrator or software developer, this shouldn’t doesn’t affect you too much. If you’re configuring your router or firewall software and you’re not sure whether an application uses TCP or UDP, you can generally select the “Both” option to have your router or firewall apply the same rule to both TCP and UDP traffic.

Wireless charging is set to become more popular with the adoption of Qi wireless charging in Apple’s iPhone 8, iPhone 8 Plus, and iPhone X. It’s also found on some Android phones, like Samsung’s Galaxy Note 8, Galaxy S8, and Galaxy S7.

Most wireless chargers use magnetic induction and magnetic resonance. They offer the promise of being able to place a device on a surface and have it charge automatically—no fiddling with cables required.

How Wireless Charging Works

Wireless charging isn’t truly wireless, of course. Your phone, smart watch, tablet, wireless headphones, or other device doesn’t need to be plugged into the charger with a wire, but the wireless charger itself still has to be plugged into a wall outlet to function. When the iPhone 5 was released without the wireless charging feature found in competing Android and Windows phones at the time, Apple’s Phil Schiller argued that “having to create another device you have to plug into the wall is actually, for most situations, more complicated”.

Five years later, Apple has changed its mind. With the iPhone 8, iPhone 8 Plus, and iPhone X, Apple is including support for wireless charging using the Qi open standard. (It’s pronounced “chee” as it’s a Chinese word that refers to the “life energy” in living things.)

Wireless chargers typically use magnetic induction. The short explanation is that they use magnetism to transmit energy. First, you place the device–like a smartphone—on the wireless charger. The current coming from the wall power outlet moves through the wire in the wireless charger, creating a magnetic field. The magnetic field creates a current in the coil inside the device sitting on the wireless charger. This magnetic energy is converted to electrical energy, which is used to charge the battery. Devices must have the appropriate hardware in them to support wireless charging—a device without the necessary coil can’t charge wirelessly.

While the Qi standard was originally limited to magnetic induction, it now also supports magnetic resonance. This works similarly, but the device can be up to 45mm away from the wireless charger’s surface rather than touching it directly. This is less efficient than magnetic induction, but there are some advantages—for example, a wireless charger could be mounted under a table’s surface and you could place a device on the table to charge it. It also allows you to place multiple devices on a single charging pad, and have all of them charge at once.

When not actively charging, the Qi charger doesn’t consume the maximum amount of power. Instead, it uses a smaller amount of power and, when it detects a device is placed on the charger, it increases the energy output.

Competing Standards: Qi vs. Powermat vs. Rezence

Wireless charging is becoming more and more common, and even more standardized. And for once, Apple didn’t create its own wireless standard. Instead, it chose to support the existing Qi standard, which many other devices also support.

However, Qi isn’t the only standard around. The Qi standard, which is owned by the Wireless Power Consortium, is ahead, but it’s not alone. In second place is the Power Matters Alliance’s Powermat, or PMA, standard. It uses magnetic induction, like Qi. The two are incompatible, though. An iPhone can’t charge with a PMA wireless charger.

Some devices are compatible with both, however. Modern Samsung devices like the Galaxy Note 8, Galaxy S8, and Galaxy S7 actually support both the Qi and PMA standards, and can charge with either. Starbucks bet on PMA, but they may rethink things now that the iPhone only supports Qi. Apple is betting that airports, hotels, and other public locations will also choose to bet on Qi.

The Alliance for Wireless Power (A4WP)’s Rezence uses magnetic resonance instead, a feature Qi added later. This allows for greater freedom of positioning. You can have multiple devices on a single charger, move devices around, and even charge devices through an object like a book between the device and the charger. Rezence requires Bluetooth to communicate with the device.

As the second and third place companies here, the Power Matters Alliance and Alliance for Wireless Power have since rebranded themselves the AirFuel Alliance and are cooperating in an attempt to take on Qi.

How You Can Use Wireless Charging Today

All the technology aside, getting started with wireless charging is pretty simple. If you want to charge your smartphone wirelessly, you’ll need a smartphone that supports wireless charging and a compatible wireless charging mat to place your phone on. You can also purchase adapters to add wireless charging support to phones that don’t include it.

Popular smartphones that support wireless charging include:

• l Apple iPhone 8, iPhone 8 Plus, and iPhone X
• l Samsung Galaxy Note 8 and Galaxy Note 5
• l Samsung Galaxy S8, S8+, S8 Active, S7, S7 Edge, S7 Active
• l LG G6 (US and Canada versions only) and LG V30
• l Motorola Moto Z, Moto Z Play, Moto Z2 Force, Moto Z2 Play (with wireless charging mod only)

Android manufacturers have increasingly been abandoning wireless charging in recent years. Only Samsung has kept it on its recent high-end phones. For example, Google does not offer wireless charging in its Pixel smartphone, although earlier Nexus phones included this feature. With Apple giving the Qi standard a vote of confidence, wireless charging could become more common on Android devices once again.

If your phone doesn’t support wireless charging, you can add support for wireless charging with a special phone case or wireless charging adapter that you stick on the back of your phone and plug into its power port.

Once you have a phone or adapter that supports wireless charging, pick up a wireless charger that’s compatible with it. For most phones, you’ll want a Qi charger. Any Qi certified wireless charger should work with any Qi certified device. You can find them online on websites like Amazon.com or in electronics stores. Plug the charging pad into the wall and place your phone (or other Qi-enabled device) on it to charge. As long as your device and the charger support the same standard, it will just work.

In the future, wireless chargers will hopefully be more common in public locations, allowing you to just place your smartphone on a table to charge it.