definition of advertising and advertisement

We now see more clearly that advertising is quite different to, and actually within, marketing:
"The activity or profession of producing advertisements for commercial products or services." (2005 Oxford English Dictionary)
Advertisement is defined as: "A notice or announcement in a public medium promoting a product, service or event, or publicizing a job vacancy." (2005 Oxford English Dictionary)
"Communicating by print or electronic or other media to a customer/audience/market about a product/service/organization so as to improve the desire for or view of the product/service/organization." (Businessballs.com, A Chapman, 2012)
(Extending usefully as:) "...Advertising seeks, in measurable, cost-effective, controllable ways, to generate enquiries or sales and/or to raise awareness/perceptions of a supplier/provider/organization, by presenting motivating communications to an appropriate audience." (Businessballs.com, A Chapman, 2012)

in summary

Marketing and advertising are different.
Marketing is an extremely broad area that includes advertising, not vice-versa.
Marketing also includes PR, online presence/activities, customer service, selling/sales admin (methods and structure/strategy), branding, exhibitions, sponsorship, new product development, merchandising, surveys and market research, political lobbying, and even extends to ethos, culture, training, and organizational constitutional issues, since all this affects the image and trading style of an organization or product/service provider.
Advertising is far more specific than marketing; advertising is a function of marketing, and basically encompasses methods of communication with audience designed to produce sales enquiries, and/or improve awareness/perceptions of product/brand/organization. Advertising refers to printed and electronic media that is presented one way or another to market or audience, including packaging, point of sale, brochures and sales literature. Advertising increasingly extends to 'advertorial' in traditional and online media, which combines provision of objective helpful information and more subjective advertising/endorsement. Advertising (when properly executed) is the statistically driven and measurable implementation of marketing strategy, via carefully selected communications methods, targeted at predetermined audiences.
Advertising is one of several instruments/means by which marketing operates.
We might also regard advertising as one means of tactical implementation of the strategic aims of marketing.