The markup that defines HTML is called tags. For example, we here have the break tag, which
is used to make a line break. All tags are delimited by angle brackets (<>) and are case-insensitive.
Most tags, such as the paragraph tag here , have both a start and an end tag. The
end tag is always the same as the start tag, but with a forward slash before the tag's
name. This combination of start tag, content, and end tag is called an element, in this
case a paragraph element. Element is also commonly used as another word for tag.
Start tags may contain different attributes and values, which are also case-insensitive.
The quotes around the value, are only required if the value includes whitespace or special
characters, but it's a good practice to always include them.