Check out example codes for "pseudo elements css". It will help you in understanding the concepts better.

Code Example 1

psuedo element(An intuitive answer):
							keywords added to selectors (which are followed by 
                            colon ':' or double colon '::') which allow to target
                            specific element (or specific part of element).
example:
 you can style the first letter of a paragraph as->  p:first-letter{/*styles*/}

STRONG NOTE:  Keep in mind that  ::first-line pseudo-element  must be applied
			  to block level (elements which break line on use)
			  elements in order to take effect.

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