In this lesson, you'll demo Celebrity Match, an application that's powered by one of the many Watson APIs: the Personality Insights API.

A Watson-Powered Application

Bluemix is IBM's cloud platform that enables developers and organizations to quickly and easily create, deploy, and manage applications on the cloud. 

Bluemix also provides developers with enterprise-level services that can easily integrate with your own cloud applications, without needing to know how to install or configure them. You can learn more details the services <a href="https://console.ng.bluemix.net/docs/overview/index.html" target="_blank">here</a>.

In the next lesson, we'll review the variety of services  available in Bluemix.

Overview: Bluemix

Let's demo a working application that showcases one of the 19 APIs available within the Watson Developer Cloud: the **Personality Insights (PI)** API. 

The name of this application is **Celebrity Match**.

The application does the following:

1. Accepts two Twitter usernames as variables
2. Retrieves the last 200 Tweets from each Twitter username 
3. Sends the text of the 200 Tweets to the Personality Insights (PI)  API (covered in more detail later in this course) to gain insights on the two users
4. Compares the users to one another 
5. Displays the results of the comparison

The final results displayed will be the top 5 traits shared between the two Twitter users (for example: you and a celebrity of your choice). 

The results are displayed in the following format:

Matched Personality Trait `->` Probability of your profile exhibiting given trait `->` Probability of Celebrity's profile exhibiting given trait. 


**Note:** To successfully run this demo, a Twitter account and Twitter API credentials are _required_. <a href="https://developer.twitter.com/en/docs/twitter-api/getting-started/about-twitter-api" target="_blank">The Twitter API documentation</a> describes how to obtain API credentials.

A Working App: Celebrity Match

Let's review what actually happened in the demo:

1. Both Twitter usernames (handles) are checked to make sure they're valid.
2. A call to the Twitter API retrieves the first 200 tweets from your Twitter feed (excluding any retweets).
3. A call to the Twitter API retrieves the first 200 tweets from the celebrity's Twitter feed (excluding any retweets). 
4. Your 200 tweets are sent as a single body of text to the Watson Personality Insights (PI) API to be analyzed.
5. The celebrity's 200 tweets are sent as a single body of text to the Watson Personality Insights (PI) API to be analyzed.
6. The Watson PI API runs a sorting & matching algorithm to find the most common attributes between both bodies of text.
7. The application prints the results to the user.

In this course, we'll build the **Celebrity Match** application from the ground up, beginning by installing the necessary Python packages, setting up Bluemix and Watson, and using the Twitter API and the PI API to display the results.

You'll need the following to build the application:

1. A <a href="https://twitter.com/signup?lang=en" target="_blank">Twitter account</a> (create an account if you don't already have one)

2. An IBM Bluemix account (you can create an account later in the course)

Let's get started!

The Application Flow

The Watson Developer Cloud is a _collection_ of <a href="https://en.wikipedia.org/wiki/Application_programming_interface" target="_blank">APIs</a> that enables developers to add cognitive capabilities to their applications. All of the APIs are available for use by applications built in Bluemix.

Specifically, The APIs offer cognitive capabilities in the following four main categories: 

* Language - use unstructured bodies of text to retrieve insights from that text. Insights can span a wide range, from the personality traits of the author who created the content to specific details on what the content is about and what it may be related to.

* Speech - interact with your users in many different languages using speech-to-text and text-to-speech.

* Vision - understand the world around you by retrieving insights on the users who created certain images. 

* Data Insight - access data pipelines and help make decisions on competing criteria.
  
Learn more about the services <a href="https://www.ibm.com/smarterplanet/us/en/ibmwatson/developercloud/doc/getting_started/" target="_blank">here</a>.