Siri is an intelligent personal assistant that started with Apple iOS 5 with the release of iPhone 4S.
It is a speech recognition technology that is implemented in the core of the iPhone 4S. It allows you to talk to your iPhone and ask it to do different things in a way that was never done before in this level of intelligence and accuracy.
The iPhone 3GS, and iPhone 4 did have what is called "voice command" which allowed you to open a song, announce the time and call a contact. It was the worst and most useless features on iPhone 4.
Other voice commands such as "TellMe" from Microsoft, and " voiceAction for Android" from google were already available 2 years before the iPhone 4S. Although Siri wasn't the first in the market, it was definitely a breakthrough technology compared to the others.
What makes Siri so unique from the competition is its intelligence. She can answer philosophical questions and can understand the meaning of your question. For example, if you say "I am hungry", she will list restaurants around you. If you say "I am drunk", she will find a Taxi cap for you, or if you say "I am sick", she will find doctor's offices next to you.
After it was released on the iPhone 4S, the competition recognized how weak their speech recognition systems were, and started to work harder to try to beat Siri. It looks like Apple started again another revolution with this intelligent speech recognition virtual assistant, and the future looks very bright for it.
Visit Siri for iOS 10 and siri for iphone to see the latest and greatest development on this technology. Also visit Siri hacks to see what the jailbreak community has done to improve this service.
What is Siri:
It is a speech recognition technology that was spun off another company called SRI International. It was founded in 2007 and was a result of 40 years of research and development of speech recognition.
An iPhone application called Siri was available on the App Store for sometime, and was planned to be ported to Android and Blackberry phones in the future. However, Apple acquired Siri in 2010, and all those plans were canceled, and the application itself was also pulled from the App Store.
How to activate it:
You can activate Siri by simply pressing and holding the home button for 2 seconds. When you hear a beep indicating that she is listening, you can then ask your question or start your conversation.
You can also start her from the lock screen. If you happen to have a security code that locks your iPhone, you will be asked to enter the code before she can access your information. Because Siri is integrated with all of the pre-installed iPhone applications like e-mail, text messages, Safari, Calendar, Reminder, Notes and Youtube. You are able to ask questions related to any of those apps.
How does it work:
When you ask Siri a question, it will connect to Apple servers and quickly interpret your question and search the Internet for an answer. Therefore, you must have an internet connection for it to function.
It goes online and search many sites including Yelp, Yellow Pages, any many other resources including google. It can also search your iPhone information for a contact phone number for example, a meeting that you have, or reminders that are in your list.
The Commands:
You can access the official Siri list of commands by tapping the "i" letter shown at the bottom corner when it is active. Or you can ask her about the guide by simply asking "what can you do", and she will come back with the list of commands.
If you tap any of the commands in the list, you will get the different ways you can ask the question. For example, tap the "Reminder" button from the guide, and you will see 4 ways to ask for a reminder.
You can experiment with the other commands and see what you could possibly ask.
This is not everything available, but it is a good starting point. I myself am still learning new commands and possible question.
Siri is still new but it is so powerful with many hidden features. Watch the videos at the bottom of this page to see some possibilities with Siri hacks.
Weather:
Finding information about the weather is pretty cool. Not only you can get the forecast for the whole weak, but Siri will announce the high and low depending on how you ask the question.
If you ask "how is the weather today", she will give the forecast for today and the rest of the week. But if you ask about the temperature like "what is the temperature today", she will announce the high and low temperatures for you. This is pretty cool when you are driving and can't see your iPhone screen.
She could also comment on the forecast, and tell you if the weather is nice or if it is not very nice outside.
The beauty of Siri is that her answers can change for the same question during the day. So, expect different answers sometimes for the same question.
History and Math:
Siri can answer questions in different areas and fields. Try a question about history like "what is the age of the Egyptian pyramids" or a question about Math like "what is the integral of X^2".
Other math questions you could ask are something like "what is 500 times 6" or "what is the square root of five times five over 2". It can answer simple and more complicated calculations.
She can also solve an equations pretty quickly. For example, say "solve for x when x+1=5", it will come back with X=4 and will show you the two lines, one line for 5 which is the red line in the picture below, and another line for x+1. The intersection is the only solution of X which is 4.
Appointments, Reminders and Alarms:
Making an appointment or a reminder could never be easier. You can simply ask her to remind you of doing things. For example, "remind me to pick up the flowers at 2 PM tomorrow". A reminder will be created.
You can ask for the reminder to be at any specific time and day. It can be tomorrow or after 10 or 20 years in the future. You can also create a daily reminder like "remind me to take my medicine everyday at 1 PM".
The same thing applied to appointments. Simply say "make a doctor appointment on Thursday at 5 PM" and the appointment will be created.
Using the same method, you can set an alarm. For example, you can say "wake me up tomorrow at 7am" or "..everyday at 7AM" to set a repeating alarm, it is that simple.
Send Messages and e-mails:
This is also a cool feature of Siri. You can use it to send an email or a text message to any of your contacts. Simply say send an email to Tom for example. If Tom is in your contact and all his information such as his email and phone number are available. Then, Siri will start an email addressed to Tom, and will ask you about your subject and what you want the email to say.
You can also send text messages to your friends in your contacts list using the same process. For example, you can say "send a text to Tom".
Speech Dictation:
It is also possible with iPhone 4S to input text by voice. When you are anywhere in any iPhone application with text entry, you can tap the microphone button to activate the speech recognition feature. This microphone button is a feature of iOS 5 but can only be seen on the iPhone 4S. It is located in the iPhone touch keyboard to the left of the space button as shown in the picture below.
Once you say what you want, tap the "Done" button, and your speech will be converted to text in the blank you choose. This is a powerful feature that could eventually limit the use of the iPhone touch keyboard.
You will be surprised how much speech is converted to text correctly even with a foreign accent. You might have to go back and correct some words but the accuracy is very high.
Start Music Library:
Speaking the song or album you want to hear can be very useful when you are driving. Siri can find the song you want very quickly. You can create a Playlist of your songs and call it whatever you like on your computer in iTunes, and then you can ask Siri to play that Playlist.
You can also ask her to play a song or an album by a specific artist in your iTunes library. Simply say "Play list name", or "Play album ..".
Other Hidden Features:
One cool feature of Siri is that it can set relations with your family. For example, you can say "Tom is my father", and she will remember this relation. Next time you call Tom, you can simply say "call my father" and she will call Tom.
Because the iPhone comes with a GPS chip, she can use the GPS information to take location specific commands since she knows where you are. She can remind you to do things when you arrive to a specific location or when you arrive home.
For example, you can say "remind me to call my wife when I arrive home", once you are close to your home, you will get a reminder.
There are many tweaks that already startled to show iPhone 4S voice power. Watch this video to see how you can control the lights in your house with voice.
The following video shows you how you could control your TV with your Voice.
With some hacks and tweaks for the voice command, you will be able to start iPhone applications, change the settings on your iPhone or even restart or power down your iPhone. Moreover, you can use your voice to translate one language to another, or even just start a long continuous conversation with your iPhone.
Visit the Voice Tweaks page to learn more about some exciting new features of this voice command for the iPhone that you can add with a jailbreak.
Also, visit siri for iphone, and siri for iOS 10 to learn more about new technologies, and development, and new features that evolved over the years since the introduction of this new voice assistant.
Siri is an intelligent personal assistant that started with Apple 
If you tap any of the commands in the list, you will get the different ways you can ask the question. For example, tap the "Reminder" button from the guide, and you will see 4 ways to ask for a reminder.
Finding information about the weather is pretty cool. Not only you can get the forecast for the whole weak, but Siri will announce the high and low depending on how you ask the question.
Making an appointment or a reminder could never be easier. You can simply ask her to remind you of doing things. For example, "remind me to pick up the flowers at 2 PM tomorrow". A reminder will be created. 
