WordPress.com is a very popular free blog hosting platform, and though ads are rarely seen on this site, they do exist. Now wordpress.com bloggers can opt for the No-Ads upgrade and ensure no one ever sees any ads on their site.
I personally have never seen any ads on wordpress.com, but they had revealed earlier that some Google Adsense ads were displayed on post and tag pages to ‘focus on free features in addition to paid and to offset costs of rapidly rising traffic”. These ads were not shown to regular readers which makes them really unobtrusive.
But if you never ever want any ad to appear on your blog for any reader, old or new, they now let you opt for the No-Ads upgrade, available for 30 credits a year ($0.08 a day) through the Upgrades tab in your blog’s dashboard.
Though WordPress.com blogs have their own benefits and limitations, they are working hard to make it better. An important benefit offered to wordpress.com users is that they get to test run new features much before they get released on the downloadable wordpress version.