From developer's perspective any site can be divided into two levels - logical and physical. On a logical level site is a collection of web pages, united by a single design, style and links.
There are a couple of cases where it is practical to use the tag base, for example, when the same images are in different structural parts of the site.
Hidden field is not displayed on the page and its content is hidden from the user. Visitor of the site can not insert or input anything into it.
Large documents are easier to read if they have a table of contents with links to relevant sections.
A constant is a named value that doesn't change while the program (script) in running.
Quite often, when creating an object it is required to set values to some properties. Fortunately, the developers of OOP took this into account and implemented it in the concept of constructor.
With CSS, you can set the style and appearance of the text.
If you want create a link to a document that opens a new browser window, set parameter target="_blank" of the a tag.
Cascading Style Sheets allow you to keep the color, text size, and other parameters in styles.
Thanks to many properties of the cell, you can change the look and design of the table.
Numbered list is a list of items each having its own numbers. The style and the type of numbered list depends on the ol tag, which is used to create it.
In CSS absolute and relative units are used to specify dimensions of various elements.
PHP does not directly support destructors. However, you can easily simulate a destructor by calling the PHP function unset.