Online ads come in various shapes and sizes. Regardless of the appearance aspects they can be broadly categorized into two – Contextual ads and Non-contextual ones.
Contextual ads are the ones which get displayed on your pages based on the context or content of your page. For example, if you are writing an article or post about ‘cake baking’ it is highly likely that the contextual ads that appear on that page (via Google AdSense or other ad networks) may contain ads of ‘Cake recipes’ sites or ‘Birthday cake’ vendors etc. Content link ads – where the actual words on the page itself forms ad links – is also considered contextual ads.
The search engines (e.g. Google) crawler of these ad networks would have already studied and stored the contents, leading words of your pages to facilitate the contextual rollout of ads. There are some networks that dynamically (or on-the-fly) understands the page contents and delivers contextual ads. Most such networks are content link ad networks.
Non-contextual ads on the other hand are not based on your content type but are generic in nature. For example, the Text-Link-Ads network promote non-contextual ads.
In most cases, affiliate ads are non-contextual in nature unless you specifically search and pick context based ones for your pages or blogs. And usually ad networks will be having only one of the above leading forms of ad marketing – either contextual or non-contextual – and that too based on various compensation methods (An article on compensation methods will be soon appearing here).
The above mentioned categories are further available in different sizes based on which they are called button ads, banner ads, blocks, sky-scrappers etc. The categories based on behaviour can be in-place ads, pop-up ads or pop-unders (pop-behinds). As the names indicate, in-place ads appear on the same page that you are reading, pop-ups appear in a different browser window on top of the page that you are reading, pop-unders appear in a window that is underneath your main browser window. There are also very innovative ways of rendering ads, such as floating-on-the-page ads, pealing ads, text-streaming ads etc.
The following are the normally found ad genres based on their look and feel.
Text link ads or text ads
These are advertisements in the text format which usually include the advertiser’s name or brand and a short description. The content further will be a link by itself clicking on which you will be redirected to the advertiser’s or vendor’s page. Contextual ads work best in this form.
Image ads are one of the oldest ad types as the basic 468×60 image or banner ad is almost 20 years old now. Image ads can be still image or animated in nature.
In some cases the combination of an image and text is also used as a composite ad block.
Flash or video ads
In this case a small video clip or flash animation appears on the browser window within an area defined by the underlying media reader applet. Video ads are the heaviest form of ads in terms of the time to download (regardless of whether they are streamed or fixed).
Audio clips are relatively unpopular form of ads. They are played when the intended web-page is loaded and usually played after a small delay. They are used more for branding purposes rather than using as ads as such. But pod-casts, audio newsletters etc can effectively use this type of ads.
There are no other ad forms that are coming to mind as of now. I request my readers to educate me if they are new and innovative ad types already out there.