What is Google Adsense ?

Google AdSense is a program run
by Google Inc. that allows
publishers in the Google Network
of content sites to serve automatic
text, image, video, and rich media
adverts that are targeted to site
content and audience. These
adverts are administered, sorted,
and maintained by Google, and
they can generate revenue on
either a per-click or per-
impression basis. Google beta-
tested a cost-per-action service,
but discontinued it in October
2008 in favor of a DoubleClick
offering (also owned by Google).
In Q1 2011, Google earned US
$2.43 billion ($9.71 billion
annualized), or 28% of total
revenue, through Google
AdSense.

Google uses its Internet search
technology to serve advertisements
based on website content, the
user's geographical location, and
other factors. Those wanting to
advertise with Google's targeted
advertisement system may enroll
through Google AdWords. AdSense
has become a popular company in
creating and placing banner
advertisements on a website,
because the advertisements are
less intrusive than most banners ,
and the content of the
advertisements is often relevant to
the website.
Many websites use AdSense to
monetize their content; it is the
most popular advertising
network. AdSense has been
particularly important for
delivering advertising revenue to
small websites that do not have
the resources for developing
advertising sales programs and
sales people to generate revenue
with. To fill a website with
advertisements that are relevant to
the topics discussed, webmasters
place a brief HTML code on the
websites' pages. Websites that are
content-rich have been very
successful with this advertising
program, as noted in a number of
publisher case studies on the
AdSense website. AdSense
publishers may only place three ad
units per page.
Some webmasters put significant
effort into maximizing their own
AdSense income. They do this in
three ways:

1. They use a wide range of traffic -
generating techniques, including
but not limited to online
advertising .

2. They build valuable content on
their websites that attracts
AdSense advertisements, which
pay out the most when they are
clicked.

3. They use text content on their
websites that encourages visitors
to click on advertisements. Note
that Google prohibits webmasters
from using phrases like "Click on
my AdSense ads" to increase click
rates. The phrases accepted are
"Sponsored Links" and
"Advertisements".

The source of all AdSense income
is the AdWords program, which in
turn has a complex pricing model
based on a Vickrey second price
auction. AdSense commands an
advertiser to submit a sealed bid
(i.e., a bid not observable by
competitors). Additionally, for any
given click received, advertisers
only pay one bid increment above
the second-highest bid. Google
currently shares 68% of revenue
generated by AdSense with content
network partners, and 51% of
revenue generated by AdSense with
AdSense for Search partners.
While creating a adsense account it will ask PAN. And your gmail id. Before that you should make an account in Google +.