Unless you are new to the Amazon Echo you have probably spoken many times to your Echo. You may have asked "Alexa, what time is it?" or maybe "Alexa, play rock radio.". Without such commands the Amazon Echo would be a fairly useless device. So how does the Echo know what to do when such commands are spoken.
The answer to this is fairly simple. Once the Echo has heard the wake word it uploads the audio up to the Amazon Alexa servers (you can hear this audio in the Amazon Alexa mobile app). Once the audio is uploaded the Alexa service decipher the content of the audio and attempts to match this up to a function that the Echo has enabled.
These functions are what is known as Skills. Skills can be split into 2 types. Firstly there are in-built skills such as the skill that enables you to play music or the skill that tells you the current time, these are created by Amazon and enabled by default. Additionally however there are custom skills that are created by third-party developers and must be enabled by the user.
Browsing the database I can see a vast array of available skills ranging from silly skills such as Cat Facts (yes a skill that gives you a random fact about cats) through to SmartThings, a skill that allows you to control a vast array of Internet Of Things (IoT) devices.
So why does Amazon allow you to create skills?
Amazon does not only allow you to create skills, they actively encourage you to do so. Amazon have ran numerous competitions on services such as Hackster.io. By allowing users to create skills they are helping increase the utility and functionality of the Echo. Users can create skills for the Echo that Amazon potentially never even considered. The possibilities are almost endless.
Enabling a skill is a rather trivial act. To enable a skill you can visit the store for your region, search for the skill and click the enable button. Alternatively you can use the mobile app.
If you would like to see the type of skills that are available for the Echo, Amazon have you covered. Amazon have created a category specifically for skills in their store: