A Mashup, quite basically, is any web application which derives data from multiple sources and then “mashes” these sources into one coherent set of data. A simple example of this, and something that happens quite frequently, is that you have a set of full street addresses that you want to display on a map. A map doesn’t have the contextual knowledge of what a “street” is — while your mind (and mine) think of places in terms of street names, cities, towns, and states, maps work within coordinate systems which define points.
So now we’re at an impasse, wondering how we can relate between what we understand, and what we can make a map understand. Lucky for us, there’s a vast number of services out there that will take in an address and spit back to us these coordinates via a process called geocoding. Google’s one of the bigger ones, and provides this service for the low cost of free. And lucky for us, they also provide free, easy-to-implement map widgets for inclusion on the site. But just in this slight example, you can start to see just how powerful mashups can be.
We just had our list of addresses; anyone can come up a list of addresses. But then you throw that together with Google’s location point data and Google’s map visualizations, and you’re getting a ton of value with very little cost.
Data like this can come from any source, and it doesn’t have to be as dry as Cartesian coordinate points either. The New York Times has a service which allows you to grab their movie reviews all the way back to the year 1924. Washington D.C offers data feeds for all kinds of city-related data, with uses extending from a carpool organizer to your own personal safety guide.
This ease of integration, matched with the tangible benefits of such services, certainly plays a large role in the adoption of a lot of these technologies. For a very low cost, I’m able to start getting a lot of related data, even if I have something as seemingly-insignificant as an address, or the time I want to go see a movie, or even the name of a musical artist. Some of the web’s biggest names are offering extensive, valuable data for free all over the place.