Held: Wednesday, 22 January 2003
Today we begin to ground our understanding of computer science
with hands-on practice. In particular, we'll look at some of the procedures
necessary for building documents for the World Wide Web.
- I'm still reading through your surveys. Expect responses by
- When you work on today's lab, you should plan to work with a
We may not cover this section explicitly, but it gives you some things
to think about.
- HTML is the markup language used for the World Wide Web.
- Unlike a programming language, which describes algorithms, HTML is
simply a markup language. Markup languages describe data.
- Some of the same questions come up as you consider how the computer
might represent any document. For example, a typical word-processed
document will have different margins, font, and justification at different
parts of the document.
- Should a human be able to tell what's going on; or can it all
- What do you have to represent in a document? Nearly everything:
- The content of the document
- Something about each piece of the document
- General document characteristics (e.g., page margins)
- We say that a language for representing documents includes
mark up symbols that indicate these characteristics.
- In considering markup, there are two general
what you mark: logical markup and physical markup.
- In logical markup, you indicate the role of each
piece of text. For example, you might indicate that
This is a paragraph
This is an important word or phrase
This is a quotation
This is the title of a book
This is a top-level section heading in a paper
- In physical markup, you indicate the appearance of
each piece of text. For example, you might indicate that
This should appear in Times Bold 12pt
This should appear in a box 2 inches each side that is placed
3/4 inch from the top margin and 5 inches from the right margin
- I'm a strong proponent of logical markup. Why?
people have different expectations about the appearance of certain
- Physical appearance does not necessarily
indicate the logical role, even when the author of a document
may intend you to do so.
- Consider book titles. What should a book title look like in a
- Consider italicized words. Why do you expect to see a
word (or words) in italics?
- I also worry that too much emphasis on physical markup leads
non-designers to commit unreadable documents.
- HTML is a simple markup language created for the World Wide Web.
- HTML is intended to be human readable.
- Some would dispute that claim.
- HTML is a particular form of SGML, the Standard Generalized
- SGML was designed by a number of scholars for representing
- Full SGML can even describe layout of pages so that one can
precisely represent documents like the Talmud.
- In HTML, parts of the document are surrounded by tags.
- Tags give information about those parts of the document.
- Each tag begins with a less-than sign and ends with a
- End tags have a slash after the less-than sign.
- For example,
- You begin a paragraph with
<p> and end
a paragraph with
- You begin an important word or phrase with
and end it with
- You begin a list of items with
end it with
- You begin an item in that list with
end it with
- You begin a numbered list with
end it with
- You begin a piece of text in a
typewriter font with
<tt> and end it with
- Some tags do not require end tags. Some even disallow end tags.
<br> is a line break. Since there's not text
that you're marking, it needs no end tag.
<br> is a horizontal rule.
<li> tag does not need an end tag
(since the next
<li> or the ending
obviously ends it).
- Some tags permit you to enter parameters: more information
about how the text should be displayed. For example, you can write
<p align="right"> for right-justified text
<hr width="75%"> for a less-wide rule
<font face="Helvetica" color="Red"> for
red, Helvetica text.
- Since much of this course is hands on, let's get started.
- See the accompanying laboratory
- Do the HTML lab.
- Raise your hand if you have a question.
- If you don't finish it all today, try to work on
it tonight (or later).
- Complete understanding of this lab is not required to progress to the
What have you learned today?
Thursday, 16 January 2003 [Samuel A. Rebelsky]
- First version, created mostly automatically from previous course.
Wednesday, 22 January 2003 [Samuel A. Rebelsky]
- Filled in introductory details.