Okay, the last thing I want to talk about as we look at information technology, Internet
information technology, is just to give you some tools so that you can look at some of
the computer language and some of the technology that is in a web page. So for starters, if
you open any generic browser, in this case the example is a Chrome browser by Google,
and you go in this case to the ics page, www.ics.uci.edu there is actually a place it the menu under
view and developer where you can look at the source code for that web page. That source
code shows you the language, the programming language of html, CSS and Javascript that
were written in order to produce that image, that web page that you see presented in the
browser. So, this is what it looks like when you view the source, at least on the day on
which we captured this for the slides. You would see stuff that looks a little complicated.
It's a little hard to read if it is the first time you have ever seen it, but it is actually
pretty understandable once you understand the different components. So, let's walk through
some of those components just you have a sense of how to parse this visually. So for starters
what we do is we do view source in order to look at the html. Usually we think of web
pages as consisting of three different pieces, html which describes the content of a web
page, Javascript which describes how the web page interacts with people as we use it, and
then CSS which stands for cascading style sheets. That describes the way that the contact
is formatted and structured to look. So, there is data, interactivity and presentation.
Html, Javascript and CSS. Together those are used to create a web page. So, html is the
language that is focused on structuring the content of these documents for publishing.
So, here is an example of a small html snippet, and you can see that there are these things
in there called tags. Tags are not actually part of the content. They are called metadata
and they are used to help format and structure the content. So you can see in this small
html document there is an html tag at the top and a /html tag at the bottom. There is
an h1 tag at the front of bananas, and there is an h1 tag at the end of bananas. Those
tags are used in order to describe some of the ways in which the content should be presented.
Links are a special kind of tag. You are familiar with links. These are things that you click
on in a web page that will take you to a different web page. So, down here at the bottom you
see a special tag. It's the a or anchor tag, and that has an attribute called href, and
href tells you what web page you will go to if you click on the task that is between the
two tags. So in this example you see that the word Peru will be shown in the web page,
and when you click on it you are going to go to the web page whose URL is Peru.html.
Again, this is just an example for demonstration purposes. Finally, cascading style sheets
are a way of officially applying visual styles to text so that fonts, colors, layouts are
the same for all the pages in a collection of web pages. So, if you have many web pages
on one domain and you want them all to look the same you might use one set of cascading
style sheets to describe the look and feel of your website. Javascript is a language
that was invented to manipulate data that is in an html page and this allows you to
have inner activity to a web page. So, it does things when you click on it. So, when
you click on a button things happen. When you hover over things, things happen. Increasingly
we are seeing Javascript not being used just as web pages, but being used in other kinds
of computing environments, in particular something called Node.js. If you are interested in learning
more about that, that is something that you could look up online. That's an environment
that uses Javascript that is not in a web page. So, the last concept that we want to
communicate to you in this series of lectures is the idea of open source software. Open
source software is a special kind of software. So, the picture here on the side shows a number
of different projects, some of which you may be familiar with, some of which may be a little
bit more obscure, but these are all software projects that have agreed or somehow support
the sharing of the software and the code that is used to create the system with each other.
Now, it's not the case that everyone has to share the software that they write. If you
do share the software that you write and you allow other people to use it and to build
on it then that is called open source software. Source code are those instructions. Those
programs that you write are called source code. Source code is compiled by compilers
into programs or apps. If you allow other programmers to use your source code, if you
share your source code then that's called open source software. Open source programmers
are usually not motivated by selling their programs. Usually they are motivated by other
things. They tend to give it away from free so that people can use it, or maybe they want
to make money on their software in other ways. For example, providing service and maintenance
for the software instead of selling the software as an object in and of itself. So for example,
Microsoft Word is an example of closed source software. You can't get software associated
with Microsoft Word. If you think about the Apache web server, the Apache web server is
open source software. You can go look at that software source code if you would like. Okay,
so in conclusion technology is made by people, people like you, people who want to change
the world using information technology. A high level process of how you create software
is first you decide what you want. How do you want the world to change? What do you
want to do with your computer? Decide that first. Next, you need to decide where it should
work. What hardware? What environment? What operating systems? What phone? What people?
What infrastructure are you going to work with? Then you need to learn the programming
languages that are associated with that environment, that digital location. Then you need to learn
and write the source code that is associated with what it was you wanted to make. You need
to compile and package the source code into an application or a program. Then you need
to get it to people somehow through an app store or through e-mail or through a website.
Then people run that source code. Then typically we think of this as an iterative process so
that when people run it they may find that you made mistakes in your source code called
bugs. Then you correct the bugs and you send out the software again. So, that's it. I hope
that is enough that we can have a good conversation about the way we can use information technology
to change the world. Thank you.