The user has the ability to focus only on the content

As the web becomes more popular, and as more people create their own personal websites, price of services tends to increase. With that price, advertising on free hosts or advertising to support a personal site, become more and more cumbersome on a user. Pop-ups, pop-unders, screen-holders, and other advertising can be distracting, confusion, and downright overloading for many users. Users with older hardware may find their web surfing slowed by perpetual downloads of, or constant pop-up or pop-under windows for, advertising. Advertisements with images or flashing text can be cumbersome and problematic to those who have issues with flashing lights and/or with limited navigation tools.

Many web sites have the following layout (or something similar to it):

Area 1:
Navigation Link
Navigation Link
Navigation Link
Area 2:
Advertising
Advertising
Advertising
Advertising
Area 3:
Advertising
Advertising
Advertising
Advertising
Area 4:
Navigation Link
Navigation Link
Navigation Link
Navigation Link
 
Advertising
Advertising
Advertising
Advertising
Advertising
Advertising
Advertising
Area 5:
Title of Website
 
Content of the website is here. All the content is here, below and between advertising and navigational structure that is complex and non-linear.
Area 6:
Advertising
Advertising
Advertising
Advertising
Advertising
Advertising
Advertising
Advertising
Advertising
Advertising

There are six areas marked out across this particular layout. They are numbered in order of left-to-right, top-to-bottom, which is how many screen readers and other navigational tools read websites. A user who uses these tools would have to wait until Area 5, the section with the content, came up before actually hearing any of the website's content.

While many users can see this layout and read the content in between the constant advertising lists, even those without special tools may find the advertising distracting or the content hard to read in the constraints of the page. Imagine a user who cannot focus on the text while moving advertising is on the corner of the user's eye, or a user who cannot find the particular topic desired in the site's structure, let alone in the complicated layout of the site.