Microsoft Cognitive Services is a set of APIs that take advantage of Machine Learning to provide developers with an easy way to analyze images, speech, language, and others.

If you have worked with or studied Machine Learning, you know that you can accomplish a lot, but that it requires a lot of computing power, a lot of time, and a lot of data. Since most of us have a limited amount of each of these, we can take advantage of the fact that Microsoft has data, time, and the computing power of Azure. They have used this power to analyze large data sets and expose the results via a set of web services, collectively known as Cognitive Services.

The APIs of Cognitive Services are divided into 5 broad categories: Vision, Speech, Language, Knowledge, and Search.

Vision APIs

The Vision APIs provide information about a given photograph or video. For example, several Vision APIs are capable of recognizing  faces in an image. One analyzes each face and deduces that person's emotion; another can compare 2 pictures and decide whether or not 2 photographs are the same person; a third guesses the age of each person in a photo.

Speech APIs

The Speech APIs can convert speech to text or text to speech. It can also recognize the voice of a given speaker (You might use this to authenticate users, for example) and infer the intent of the speaker from his words and tone. The Translator Speech API supports translations between 10 different spoken languages.

Language

The Language APIs include a variety of services. A spell checker is smart enough to recognize common proper names and homonyms. And the Translator Text API can detect the language in which a text is written and translate that text into another language. The Text Analytics API analyzes a document for the sentiment expressed, returning a score based on how positive or negative is the wording and tone of the document. The most interesting API in this group is the Language Understanding Intelligence Service (LUIS) that allows you to build custom language models so that your application can understand questions and statements from your users in a variety of formats.

Knowledge

Knowledge includes a variety of APIs - from customer recommendations to smart querying and information about the context of text. Many of these services take advantage of natural language processing. As of this writing, all of these services are in preview.

Search

The Search APIs allow you to retrieve Bing search results with a single web service call.

You can use these APIs. To get started, you need an Azure account. You can get a free Azure trial at https://azure.microsoft.com/.

Each API offers a free option that restricts the number and/or frequency of calls, but you can break through that boundary for a charge.  Because they are hosted in Azure, the paid services can scale out to meet increased demand.

You call most of these APIs by passing and receiving JSON to a RESTful web service. Some of the more complex services offer configuration and setup beforehand.

These APIs are capable of analyzing pictures, text, and speech because each service draws on the knowledge learned from parsing countless photos, documents, etc. beforehand.
 
You can find documentation, sample code, and even a place to try out each API live in your browser at https://azure.microsoft.com/en-us/services/cognitive-services/

A couple of fun applications of Cognitive Services are how-old.net (which guesses the ages of people in photographs) and what-dog.net (which identifies the breed of dog in a photo).

Below is a screenshot from the Azure documentation page, listing the sets of services. But keep checking back, because this list grows and each set contains one or more services.

 
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