 Now, let's look at a few more of the essential tags. The tags H1, H2, H3, H4, H5, and H6 are all header tags, and the difference between them is they're just different levels of header. And header in this context is not the same as the head of the document itself, but within a document you have different sections and you announce those sections with a header. So things like the typical, say, academic paper, you have different sections and they each have their own header. So H1 is the top level header, it's sort of like the title at the top of the paper, and then for subsections they're in, you announce them with a second level header, an H2 tag, and then for subsections within those sections you would use a third level header, an H3 tag to announce those subsections, and so forth. And then for the actual meat of your text, the actual paragraphs that make up those sections you use the paragraph tag, the P tag. So in our example here we have a document with three paragraphs and also a first level header and a second level header. And notice that the real practical difference of these tags is basically just the size of the text. So H1 tags are the biggest, H2 are somewhat smaller, and H3 tag is going to be somewhat smaller than that, and so on down the line to H6 being the smallest. And then paragraph tags have the smallest text of all. Also note here that adjacent paragraph tags and adjacent header tags have some vertical space in between them. Now keep in mind that the primary intent of these tags is not to impose style, that is not to produce an end-visual effect in your document of this text is bigger than that text. The second point is to let you structure your document in a logical fashion where your headers are placed in header tags and the meat of your text is placed in paragraph tags. And while these tags do have different visual effects, that's all just style. And as we'll see later, style is something that you can actually modify with CSS. So for example, if you want your H1 tags to be bigger or to be smaller or to be in bold or to be a different color, or if you want your paragraphs to be noted by indentation of the first line rather than separated by vertical space, these are things you can do in CSS. You can modify the default behavior and appearance of these tags. So we'll get to CSS in a bit, but keep in mind that when it comes to writing your documents you should think first in terms of logical structure, and that's how you should choose your tags. And then if you don't like the default look given to those tags, well, you can change it in CSS. The OL tag is short for ordered list as in a list in which the order of the items is significant such that generally you want them numbered from one down to however many things you have. And inside the order list tag you include LI tags, LI here standing for a list item. And so each LI tag constitutes another item of the ordered list. So as you can see here the default style of presentation for an ordered list is that each list item starts with a number, with a dot after it starting from one down to however many list items you have. The UL tag standing for unordered list works very much the same as just for a list where the order of the items is not significant. So they're just presented with bullets rather than numbers. The table tag is intended for the presentation of tabular data, that is data presented like a spreadsheet with a bunch of rows and columns. Inside the table tag for each row you place a TR tag, TR standing for table row and then in each TR tag you place any number of TD tags, TD standing for table data and these TD tags are the cells that make up the table. So in this example here we have two table rows, two TR tags and in the first row we have two TDs, two table data tags so there's two cells there but then in the second row we have three. So the table ends up being a two by three table just that in the first row the last cell is empty because the second row had one more TD tag. And also note here that the default presentation is to simply have the items arranged in a neat grid with no vertical or horizontal lines separating them and no border around the table but there are attributes that allow us to add in such things and also there are actually CSS properties that also allow greater control over the borders and the divisor lines between the different cells and also allows for control of the positioning within the cells and the padding within the cells and so forth. The div tag is one of the most important tags. Div here stands for either divider or divisor or division. I'm not certain which I would probably say division. Any case a div tag is a generic rectangular container for text content and other tags. It's actually almost exactly like a paragraph tag except that paragraph tags have the default behavior where adjacent paragraph tags and paragraphs adjacent to headers have vertical space between them where as you see here that's not the case we have these two divs one immediately after the other and the second div and the first div aren't separated by extra vertical space which would not be the case if these were paragraph tags if they were p tags. So as you'll see when we get into CSS you'll find that most page layouts are designed by breaking them down into a bunch of divs and divs within divs and then using the CSS we position the divs we set their widths their heights their positions relative to each other and so forth. So again the div tag is a generic rectangular container for content for text and other tags but there's another generic container tag called span except span is not used to contain rectangles it doesn't form a rectangle it's used to contain any amount of text even text that flows across different lines you know that gets broken up into multiple lines. So here for example in this div tag we have a bunch of text content and I can take any of this text content this inline content as it's called and place it inside a span tag and while that in itself doesn't do anything it will not change anything here putting you don't stop in the span tag but what it allows us to do we'll see is with CSS then apply style just to the text within that span. So if I want just this text within the div to say be bright red I put it in the span and then using CSS make the text in that span bright red and the rest of the text in the div would be unaffected.