Answer

• Existence selector : Check the existence of an attribute in the tag for example p[id]
  
• Equality selector: Ensure to select tags with the specified value of an attribute. e.g. p[id="summary"]
• Space selector: Look for values with space separated words, one of which is exactly the specified word. e.g. p[calss~="xhtml"]
• Hyphen selector: Helps in selecting the tags based on the value of attributes start with a specific character sequence. e.g. p[language|="en"]
• Prefix selector (CSS3): select tags with any value of attribute begins with specified characters. e.g. p[attr^"b"]
• Substring selector (css3): Looks for contains in the value of attribute e.g. p[attr*"b"]
• Suffix selector (css3): Looks for attribute value ends in specified value. e.g. p[attr$"x"]

Answer
The Descendant Selector: This selector matches an element type that is a descendant of another specified element (or nested inside another specified element), not just a direct child. 

Answer
The following selectors were applied on the text of the question: 

Answer
Grouping:

Universal Selector

*.warning and .warning are equivalent

Type Selectors:

h1 { font-family: sans-serif }

Id Selector:

#para1

{text-align:center;color:red;}

Child Selector:

td > b {}

Answer
The advantages of external style sheet are as follows

(1)It saves you repeating the same style rules in each page.

(2)You can change the appearance of several pages by altering just the style sheet rather than each individual page.

(3)Once a visitor to your site has downloaded the CSS style with the first page of your

site that uses it, subsequent pages will be quicker to load.

(4)Because the web pages do not contain the style rules, different style sheets can be

attached to the same document.

Answer

• It saves you repeating the same style rules in each page
• You can change the appearance of several pages by altering just the style sheet rather than each individual page.
• Once a visitor to your site has downloaded the CSS style with the first page of your site that uses it, subsequent pages will be quicker to load.
• Because the web pages do not contain the style rules, different style sheets can be attached to the same document.