This word seems to have several connotations in this InformalHistoryOfProgrammingIdeas:

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'''Standards and Specifications'''

In many standards-track documents several words are used to signify the requirements in the specification.  These words are often capitalized.  The words are often placed near the beginning of the document. 

Key words: "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" 

'''HTML Keywords'''

Keywords are located in a Meta tag of an Html Page. They are most commonly used by search engines to identify content.

Resources for HTML Keywords:
	* http://www.SearchEngineWatch.Com  
	* http://www.GoodKeyWords.Com -- A freeware program used to discover the most searched KeyWords. Useful for improving hits in search engines.

'''ReservedWords'''

In programming language syntax definition. A synonym for ReservedWords.

'''Keyword Blocking '''

Used in software for blocking access

Filtering packages which use keyword blocking have a list of 'forbidden words' which they search for in web pages, e-mail messages or even Internet Relay Chat and other 'chat' functions. If the software finds those words it will either prevent the user from accessing those e-mail messages or pages or block out the relevant sections of it. The list of 'forbidden words' may initially be set by the software provider although some filtering packages will allow additional words to be added by the software purchaser. 

Libraries are particularly interested in software having this feature. It is used in this context to shield minors from language and other content inappropriate for that age group.