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.

Should you leave your laptop plugged in and charging when you’re not on-the-go? What’s best for the battery? It’s a tough question, and there are quite a few contradictory recommendations out there.

You Can’t Overcharge the Laptop’s Battery

It’s important to understand the basics of how the standard lithium ion (Li-ion) and Lithium polymer (LiPo) batteries in modern devices work. There are a lot of battery myths out there.

There’s no way to “overcharge” these batteries. When you get to 100% charge and leave your laptop plugged in, the charger will stop charging the battery. The laptop will just run directly off the power cable. After the battery discharges a bit, the charger will kick into gear again and top the battery off. There’s no risk of damaging the battery by charging it over its capacity.

All Batteries Wear Down Over Time (For a Few Reasons)

Your laptop battery will always wear down over time. The more charge cycles you put the battery through, the more it will wear down. Different batteries have different ratings, but you can often expect about 500 full charge cycles.

That doesn’t mean you should avoid discharging the battery. Storing the battery at a high charge level is bad for it. On the other hand, letting the battery run down to completely empty every single time you use it is also bad. There’s no way to just tell your laptop to leave the battery at about 50% full, which might be ideal. On top of that, high temperatures will also wear down the battery more quickly.

In other words, if you were going to leave your laptop battery in a closet somewhere, it would be best to leave it at about 50% charged capacity and make sure the closet was reasonably cool. That would prolong the battery’s life.

Remove the Battery to Avoid Heat, if You Can

Here’s one clear thing: Heat is bad. So, if your laptop has a removable battery, you may want to remove the battery from the laptop if you plan on leaving it plugged in for a long time. This will ensure the battery isn’t exposed to all that unnecessary heat.

This is most important when the laptop runs very hot—like a powerful gaming laptop running demanding PC games, for example. If your laptop runs fairly cool, you won’t see as much benefit from this.

Of course, many modern laptops don’t have removable batteries anymore, so this tip won’t apply in those cases.

But Should I Leave It Plugged In or Not?

Ultimately, it’s not clear which is worse for a battery. Leaving the battery at 100% capacity will decrease its lifespan, but running it through repeated discharge and recharge cycles will also decrease its lifespan. Basically, whatever you do, your battery will wear down and lose capacity. That’s just how batteries work. The real question is what makes it die more slowly.

Laptop manufacturers are all over the place on this. Apple used to advise against leaving MacBooks plugged in all the time, but their battery advice page no longer has this piece of advice on it. Some PC manufacturers say leaving a laptop plugged in all the time is fine, while others recommend against it with no apparent reason.

Apple used to advise charging and discharging the laptop’s battery at least once per month, but no longer does so. If you’re concerned about leaving your laptop plugged in all the time (even if it’s a PC laptop), you might want to put it through a charge cycle once per month just to be safe. Apple used to recommend this to “keep the battery juices flowing”. But whether this will help depends on the device and its battery technology, so there’s really no one-size-fits-all answer.

Occasional Discharge and Recharges Can Help “Calibrate” the Battery

Putting your laptop through an occasional full charge cycle can help calibrate the battery on many laptops. This ensures the laptop knows exactly how much charge it has left and can show you an accurate estimate. In other words, if your battery isn’t calibrated properly, Windows may think you have 20% battery left when it’s really 0%, and your laptop will shut down without giving you much warning.

By allowing the laptop’s battery to (almost) fully discharge and then recharge, the battery circuitry can learn how much power it has left. This isn’t necessary on all devices. In fact, Apple explicitly says it’s no longer necessary for modern MacBooks with built-in batteries.

This calibration process won’t improve the battery’s lifespan or make it hold more energy—it will only ensure the computer is giving you an accurate estimation. But this is one reason you wouldn’t to leave your laptop plugged in all the time. When you unplug it and use it on battery power, it might show you incorrect battery life estimates and die before you expect it to.

Your laptop’s battery isn’t going to last forever, and it will gradually have less capacity over time no matter what you do. All you can do is hope your laptop’s battery lasts until you can replace your laptop with a new one.

Of course, even if the capacity of your laptop’s battery declines, you’ll still be able to keep using it while plugged into a power outlet anyway.