Siri was Apple’s “one more thing” at the end of the iPhone 4S press event and it’s left a lot of people rather curious about this feature described by head of product marketing at Apple, Phil Schiller, as the best thing on the iPhone, not once but twice.

If you’re asking yourself, what is Siri, you’re not alone. As ever, we consider it our job at Pocket-lint to unravel technobabel to the point where normal people can actually work out for themselves whether something is good or not before it becomes another buzzword that gets used to sell you something. So here is everything there is to know about Siri. The lot.

In short, Siri is a built-in, voice-controlled personal assistant for the iPhone. The idea is to offer you a seamless way of interacting with your mobile without having to tap away at the touchscreen to find what you’re after. Instead, you speak to Siri and Siri speaks back to you. You can ask it questions for which it has to find the answer or issue it with commands for Siri to execute on your behalf, more or less hands-free.

In many ways, Siri is an app of apps. It has access to just about every other built-in application on your iPhone - Mail, Contacts, Messages, Maps, Safari, etc - and can call upon those apps to present data or simply search through their databases whenever it needs. The advantage to that is that Siri does all the leg work for you, thus you can carry out a single task with a single app even if you would otherwise need to open multiple ones in order to achieve your goal.

Now, while that sounds all very well and good on paper, there are a couple of practical issues which the developers have had to solve in order for it to work properly. The first is that the voice recognition software needs to be good. It’s no use if it can’t understand what you’ve said. Fortunately, that appears to have been well handled. The other, and more subtle, issue is that you don’t want to have to rethink the way you speak in order to get your meaning across and it’s here where Siri appears to excel. Apple claims that you can talk to Siri like a person. It understands what you say and what you meant when you said it. Press and hold the home key for a few seconds and away you go.

A lot, is the short answer to that one. Siri can read your messages out to you when you receive them and it will reply using your words without you having to type a thing too. It can give you directions. It can answer factual questions by opening the web browser and searching for the answer. It can set alarms for you; as many as you like. It can even set reminders which can activate only when it recognises that you’re in or have left a certain location (“Pick up dry cleaning”, when you leave work, for example).

Siri will play music for you in the same way that the Voice Control app which it replaces used to do on iOS. It can set calendar events. It can set timers and, indeed, you can use it to dicatate any lines of text for any text entry field on the iOS system. When the keyboard pops up, you’ll see a microphone icon to allow you to tap and start talking.

Probably most impressive of all is when Siri combines the above to service your needs. For example, you could ask Siri:

"Where can I find some good currywurst around here?"

Siri would then find your position using the GPS function, search the web for German food outlets in you vicinity, present them to you in order of rating according to web reviews and finally offer you directions on how to get to your chosen establishment. (Incidentally, if you’re anywhere in the London area, it’ll be Herman Ze German on Villiers Street, WC2N 6NE that should be top of the list.)

Essentially, Siri is designed to fulfill just about any of your needs. You tell it what you want and it will use all the apps in its power to bring you back the info you’re looking for.

Siri is based on the based on the fields of Artificial Intelligence and Natural Language Processing, and it has three components - a conversational interface, personal context awareness and service delegation

The first of the three describes how it understands you in the first place. The general workings of the straight word-for-word voice recognition have to be good in order to hear what you’re saying but deciphering the meaning is all down to statistics and machine learning and that’s where the personal context awareness system comes in. There’s a huge amount of work in Siri that can predict what you’re getting at based on key words that you use as well as your general habits and language choice. In fact, it’s designed to adapt to the user's individual preferences over time and even begin to personalise results.

It sounds complicated and it probably is but think of it as a multimedia extension of the same kind of mechanism as the text prediction service Swifkey that you find on Android. Swiftkey can present you with the next word you’re looking for before you type it because it has an idea of what you’re going to say from what you’ve said in the past and the words immediately before. The Siri system does something similar when interpreting your needs from how you talk.

Finally, at the bottom of the stack, is the service delegation system which is something that we can only imagine has improved leaps and bounds since Apple itself has taken the software on giving it unbridled access to all of the iPhones built-in apps and their inner workings. It should be an even smoother experience than the original version and it's going to have to be to fit into the iPhone way.

Siri was originally an app in its own right available for free on the iTunes App Store. (It’s since been pulled before you try to find it.) The brainchild of developers Dag Kittlaus (CEO), Adam Cheyer (VP Engineering), and Tom Gruber (CTO/VP Design) and together with Norman Winarsky, Siri was founded in December 2007 as an offshoot of the SRI International AI Center, which itlsef has roots in a DARPA-funded project that was once described as “perhaps the largest artificial-intelligence project ever launched”. And when we say DARPA, yes, we mean the US military research agency of future thinking techno-boffins.

Siri was acquired by Apple on 28 April 2010 for a rumoured $200m sum and has now been made famous by Tim Cook and pals. Its origins might explain why it’s not called iAssistant or PA or such.

So far the list includes: OpenTable, Gayot, CitySearch, BooRah, Yelp, Yahoo Local, ReserveTravel and Localeze for all the restaurant and business questions and actions; Eventful, StubHub and LiveKick for events and concert information; MovieTickets, RottenTomatoes, New York Times for movie information and reviews; True Knowledge, Bing Answers, and Wolfram Alpha for factual question answering; and Bing and Google for web search. So, pretty bloody comprehensive, then.

Naturally, there are some big hitters missing like TripAdvisor, Time Out, IMBD and such but others are expected to be adding as the Siri service grows.

Yes. Good question. Yes, it does. Apple hasn’t been specific about this but there’s data in the app, data in the Apple service centre and obviously data on the Internet at large for many of those connected services. You can access that data either over 3G or Wi-Fi but it’s not clear what Siri will be able to do for you, if anything, when you’ve got no connection.

We’d like to think the simples of setting alarms and timers would be allowed with no coverage or Wi-Fi but, it’s very possible that the language recognition and/or interpretation systems are cloud-based which would effectively render Siri useless under such unconnected circumstances. Fingers crossed, Apple has thought this one through. Right, Tim? Right?

Well, possibly but it’s got no time for anyone in South America unless you happen to speak English, French or German as well as your native Spanish, Portuguese or Dutch (French Guiana, the Falkland Islands and Guyana excepted). What we’re trying to say is that Siri will only recognise and speak French, German, US English, Australian English and real proper English English for now. God save the queen, etc, etc.

Other launguages are promised at a later date.

Probably not. Siri is going to be unique to the iPhone 4S for the time being; mean, old Apple. So you’ll have to buy one from fresh in order to get it. Jailbreaking iOS 5 might buy you some joy but that remains to be seen.

Otherwise, if you happen to be on Android, there are a few similar but probably slightly less smooth services including Google’s own voice recognition system which, sadly, is cloud-based.

Siri might turn up on other iPhones once Apple has seen that the A5 chip can handle the app with ease. It might not, though.

Well, the iPhone 4S release date is 14 October 2011. You can pre-order yours from 7 October.

Another good question. Maybe. If enough of it still works when you have no internet connection, then that’s the first hurdle to success surmounted. Next up, Apple needs to convince people to use it and that barking orders at an inanimate object in public doesn’t make you look silly. Arguably, Siri could remain something that you use in private but that rather wipes out a mass of use cases and possible the will to persist with it at all.

The true key to its future is if it’s smooth and actually saves you time. It’s a bit of a worry that the previous Voice Control effort has never quite got the traction it needed to be called a hit and having to press a button to activate a voice system is a bit of a chore in the first place but we’ll have to leave it for the iPhone 4S review before we know any more.

It is worth noting that Siri is only officially in beta, so expect a few blips. Phil Schiller’s face when he mentioned that fact at the keynote rather tells you exactly how concerned you should be. On the plus side, once it’s in full swing, it should come with a better stack of languages and services as well as a better ride too.

Not any more you don’t. Apple will be wiping that app remotely from your handset on 16 October which gives you two days to pretend that you own an iPhone 4S. Yeah, sorry about that. (Except they’re not).

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