The Software Domain: Applications

Application programs (or "apps" for short) are the programs that users interact with. Here are some uses of such software that you may be familiar with:

• Communication. You use a browser to view web pages on the World Wide Web. You keep in touch with friends using social networking, email, text messages, and chat applications that can be text-based, audio-based, or video-based. You can also tell the world what you think in a blog (short for weblog) or a vlog (short for video blog).
• Audio. Your computer or phone almost certainly has an application to play music—either from your own collection or from an Internet radio server. You can also use software to create music by using synthesizers that make new sounds, sampling (reusing) existing sounds, and recording sounds around you. For example, instead of being limited to someone else's music selections on the radio, apps like Pandora create an individualized radio station just for you.
• Pictures. You likely have a photo viewing application on your own computer or phone. You can also use software to manipulate pictures to create artwork, sharpen the focus, or create "fake news" by combining unrelated images. For example, when you get x-rays, the results are emailed to the doctor right away instead of having to wait for the images to be developed.
It would be great to have a funny picture here—maybe Obama shaking hands with an alien or something obviously fake like this (but not as creepy)... --MF, 11/13/17
Brian wants it to not be political (maybe a rock star or something). I agree. --MF, 12/8/17
• Video. You can use streaming video services to watch movies online, or you can create your own. You can shoot movies on your phone, edit them by combining video from different sources, and upload them to the Internet or burn them onto a DVD to share them with your friends. Professional movie-making uses computer animation to create special effects like space aliens, armies of soldiers, and super heroes jumping over buildings.
• Your programs. The projects you've been creating in Snap! are apps too!

There are other kinds of software that aren't for personal use but are used in industry and universities. Software applications are written to guide rockets, to analyze the results of experiments, and to design buildings and cars. Software is even written to write software.

• The amount of information available on the Internet is huge. Computers can learn to combine information from different sources, to produce surprising results. This is called data mining. For example, businesses can combine location information from your phone with similar information from other phones to find traffic jams or popular restaurants. Or they can combine multiple sources of online information about you to send you targeted advertising for products you're likely to want or to keep track of your political views for voter registration drives.
• Computers can be taught to generalize from the information they find to patterns they can use to predict the future. This is called machine learning. For example, scientists teach computers to explore telescope observations to learn new things about how the physical universe works.
• You can use spreadsheets to manage your budget or to make charts and tables. Spreadsheets are a computer implementation of what was previously a pencil-and-paper process; they are the application that made businesses take personal computers seriously.

As new kinds of hardware are invented, new kinds of software become important. For example, the invention of the smartphone, which is always with its owner, has enabled applications such as song identification: you hear a song you like that you haven't heard before so you hold your phone up, and it samples the sound and finds it in a song database. Because our phones are almost always on, they can collect information about where you are. This can be desirable when you look for friends who have agreed to share location information with you, but it also may allow your employer to find out that you took part in a political demonstration for or against civil rights.