Targeted Marketing:

The act of making the right offers available to the right customer at the right time.

So, I added “available” to the definition, although I think that might just have been a typo from the original article online.  Like visitor segmentation, targeted marketing will boost conversion rates by giving the visitors what they want.
I’ll take [...]

Visitor Segmentation:

Differentiating of users to site by categories such as age, sex, etc.

Being able to segment your visitors helps to target the ads best.  You can look at what pages different segments are spending the most time at and offer up the most relevant ads to that segment on that page.
Having ads more targeted to [...]