Siri has become one of the iPhone's defining features, but many people don't see it as a very useful one. While some of this is due to the limitations of voice recognition, it's also down to the fact that most iPhone users don't realize all the different things Siri can do.

It's easy to assume Siri isn't good for much more than finding directions or calling your contacts, but that couldn't be further from the truth. So, here are the most surprising things to do with Siri that take your virtual assistant experience to the next level.

1. Refer to People by Their Relationship to You

Everyone knows you can use Siri to call people, but it feels a little strange using someone's full name to do this if you usually call them Mom or Dad.

Well, you'll be surprised to find that you can teach Siri your relationship with other people. Then, you can use those relationships for more natural-sounding voice commands, like "Hey Siri, call my dad" or "Hey Siri, call my boyfriend."

Siri won't know who your dad or boyfriend is unless you tell it, which might explain why Siri doesn't find those contacts at the moment.

But all you have to do is say, "Hey Siri, John Smith is my father," for example, and Siri adds that information to the relevant contact card.

For this to work, you need to make sure there's a contact card for yourself on your iPhone. It should appear at the top of the Contacts app saying My Card. If it doesn't, create a new contact card and go to Settings > Siri & Search > My Information to make it your own.

2. Figure Out the Tip (and Other Math Problems)

Siri is hooked into Wolfram Alpha, which makes it capable of working out a wide range of math problems. All you have to do is tell Siri the problem you need solved and wait for it to spit out the answer.

So, if you want to figure out an 18 percent tip on a $55 bill, just ask, "What is 18 percent of 55 dollars?" You could also specify different currencies or even convert one currency to another.

But Wolfram Alpha makes it so Siri can do more than just calculate a tip. As long as you know how to ask it, Siri can handle just about any math problem you throw at it. That includes working out the square root of a number, plotting exponential graphs, or even calculating the volume of a simple shape.

3. Find a Restaurant and Make a Reservation

When you use your iPhone to find some food, Siri can suggest nearby restaurants to suit your tastes. Just ask Siri to find an Indian restaurant, takeout food, Italian cuisine, or whatever meal you're in the mood for.

Once you've done that, tell Siri to make a reservation by saying, "Hey Siri, book a table." Siri will ensure the restaurant is reservable and then offer to start a phone call to make your reservation.

With the OpenTable app, Siri can even make reservations on your behalf. Install OpenTable from the App Store and set up an account to try this for yourself. The next time you book a table with a supported restaurant, Siri can do it all for you without speaking to real people.

Download: OpenTable for iOS (Free)

4. Check Movie Showtimes and Play Trailers

Perhaps after dinner with friends, everyone decides catching a movie would be great. But what should you watch? Ask Siri what movies are showing now to check the local showtimes and get a rundown of your movie options.

If you still can't decide what to watch, Siri can also play you the movie trailers. Ask Siri to "Play the trailer for [movie name]." If it's a fairly recent movie, Siri will instantly find and play the trailer.

Siri pulls trailers from a few select websites, so if there's nothing on those sites, the voice assistant won't be able to find anything either. You could even use the trailers to decide what to watch before downloading a movie on your iPhone.

This is a good alternative if going to the theater isn't an option or you simply don't want to leave the house.

5. Keep Your Commands Private

Talking to Siri feels a little awkward in public, especially if everybody can hear the full back-and-forth between you and your iPhone. Heck, it might even earn you more judgmental looks than using a Bluetooth headset in a crowded elevator.

But don't worry, you can conversate with Siri discreetly as well. By default, Siri's Spoken Responses are set to Automatic on your iPhone, meaning it will use on-device intelligence to determine when to speak. You can double-check this by going to Settings > Siri & Search > Siri Responses > Spoken Responses.

However, you can use the Mute switch on your iPhone to enter Silent mode and make sure Siri doesn't speak out loud. Plus, you can keep your side of the conversation private by using the Type to Siri feature, which you can access by going to Settings > Accessibility > Siri.

6. Search Specific Web Pages

You probably know that Siri can search the web. Siri usually tries this when it doesn't understand your initial command. But you can intentionally tell Siri to search the web as well, which saves opening a web browser and typing a search term yourself.

You can say, "Hey Siri, search the web for [your search terms]." Or, if you'd rather use a specific search engine, say "Search Bing for [your search terms]."

Another way to narrow results is to specify the particular site you want to search. The phrase "Search for the American Revolution" will bring up your default search engine results. But if you say "Search for the American Revolution on Wikipedia," it will bring up the specific Wikipedia entry instead.

And this tactic doesn't just work with Wikipedia. You can also search many other websites, although you may need to tell Siri the specific URL with less common sites.

7. Learn to Pronounce Your Name Properly

Siri is always improving at learning new words and commands, but your assistant might still have trouble pronouncing people's names correctly. To be fair, real people mispronounce names all the time as well. At least Siri can remember the correct pronunciation forever, which is more than we can say for most humans.

Use the voice command, "Hey Siri, learn how to say my name," or try teaching it someone else's name instead. Siri first asks you to say that person's name and then mimics your pronunciation. You can choose between a few different pronunciation options each time, making it easy to get Siri sounding just right.

After you teach Siri how to say someone's name, it'll remember that pronunciation forever. You could also use a similar trick to change what Siri calls you by saying, "Call me Mr. Fantastic," or whatever other nicknames you prefer to go by.

8. Roll a Die With Any Number of Sides

Whether you lost the die in your favorite board game or you're getting into Dungeons & Dragons for the first time, Siri can make rolling dice far easier than throwing the bones yourself.

This is one of the most surprising things Siri can do because it's such a comprehensive command. Ask Siri to roll a regular die, a 3-sided die, 20-sided die, or whatever size you need. Siri will give the result instantly, much quicker than tossing one.

You can use this command to make board game night go smoothly or to help you make difficult decisions. Asking Siri to flip a coin might be the more traditional route for the latter option, though.

9. Find a Song From the Lyrics

You probably know you can tell Siri to play your favorite song, but did you know you can ask Siri to find a song without the title? It's a quick way to find a song if you just remember a portion of the lyrics instead of typing them out in Google Search.

This method is also far better than using lyrics to search for a song on Apple Music because Siri does all the work for you, including playing the song in the Apple Music player, in a fraction of the time.

All you need to do is tell Siri to "play a song with the lyrics...", then quote the lyrics you remember. For example, the command "Hey Siri, play the song with the lyrics, 'I got my peaches out in Georgia'" will prompt Siri to play Peaches by Justin Bieber.

Siri shows you other options that may be related to your search directly below the player, just in case it didn't quite get your request right.

10. Search for Tweets

Nowadays, one of the most common ways to find out what's going on in the world is by scrolling through your Twitter feed. Of course, you can do that in a matter of seconds, as it's not a complicated process at all.

But sometimes, you may want to catch up on what's happening on Twitter while cooking or being preoccupied with something else. Thankfully, you can ask Siri to search for you.

Just tell Siri who or what to search for, and it will bring up a list of relevant links to tweets. You can click on these to open them on Twitter.

Siri is so multifaceted that you can do so much with it, as you've seen. You can even ask Siri funny things on your iPhone or Mac and so much more.

Learn All the Best Things to Do With Siri

The surprising Siri commands above should give you a small taste of all the different things Siri can do. But this is only the tip of the iceberg.

Siri is an immensely powerful iPhone feature when you learn to use it properly, so don't turn Siri off, and be sure to learn all of its many commands.