Google AdSense: Alternate Ads And PSAs

Let’s take the concept of AdSense a bit further and check out 2 special case Ads:
One that is served by AdSense as per its wish and the other that is served by
AdSense as per website owner’s wish:
We all know that Google AdSense works by serving targeted Ads to the websites
that are enrolled with the Google AdSense program. However, there are
instances when no targeted Ads are available for a website e.g. the website
might be catering to such a topic or subject for which no relevant Ads/advertisers
are available. In such a case, Google serves alternate Ads i.e. content of your
choice. If you have not specified any content as Alternate Ads, Google AdSense
program treats PSAs i.e. public service Ads as alternate Ads and serves them on
your website. These PSAs are charitable Ads that don’t contribute to your
revenue. So, unless you are looking to do charity (which could mean lessening of
revenue for you), you must specify Alternate Ads upfront.
Here are the options that you have for alternate Ads (your choice of content):
Color: A number of people use color for alternate Ads. This involves specifying a
valid hexadecimal color code (or you can choose from the color palette provided
by Google) for the alternate ad. The choice of color would be such that the ad
becomes invisible. This is easily achieved by setting the color of the ad same as
the background color of the page.
Image: An image can also be used as an alternate ad. You can either have this
image link to some other web page (in such a case you will need to specify an
html as alternate ad) or you may just use it as such (for, maybe, enhancing the
beauty of your web page).
Another good option is to use ‘Collapsing ad units’. ‘Collapsing ad units’ code
will squeeze the ad units that are not utilized (instead of showing the PSAs) on
your website. This approach helps in giving a cleaner look to the web page (since
the blank areas or non-ad-based images are done away with). It also helps in
bringing more emphasis to the AdSense Ads that are displayed on the website.