1. Behavioral retargeting (also known as behavioral remarketing, or simply, retargeting) is a form of online targeted advertising by which online advertising is delivered to consumers based on previous Internet actions that did not in the past result in a conversion (in other words, the action intended by the site owner, typically making a purchase).[1]
[edit] Retargeting practices
Some companies specialize in retargeting. Other companies have added retargeting to their list of methods of purchasing advertising.[2] Retargeting helps companies advertise to website visitors who leave without a conversion -- about 98% of all web traffic. This is done by displaying ads to the prospect as they surf the internet via various ad networks that the agency buys media from on behalf of their Business Customers. Retargeting is only serving banner ads to people who have shown at least some amount of engagement in your brand. This makes retargeting a smarter spend than most other display ad campaigns as it focuses on your brand’s engaged userbase.[3] Most likely a company has spent marketing dollars to get a customer to their site in the first place, so the term Retargeting is derived from the concept of marketing to them again, however in a different manner. Search retargeting, a form of behavioral retargeting, can also be leveraged to drive new customers that have not been to the site before because they are being retargeted based on actions taken on a third-party website.
Studies suggest that a company needs to have seven different 'contacts' with a customer (on average) before they make a purchase. Retargeting is allowing companies to continue the marketing conversation with a customer after they leave a website. This form of behavioral targeting is a growing trend in the online marketing arena.
Personalized Retargeting, a related practice, differs from Behavioral Retargeting as it allows an advertiser to display a banner created on-the-fly for a particular consumer based on their specific browsing behavior. For example, if a consumer visits an advertiser's website and browses products A, B and C - they will then be retargeted with a display banner featuring the exact products A, B and C that they previously viewed.[4]

2. Digital signal processing (DSP) is concerned with the representation of signals by a sequence of numbers or symbols and the processing of these signals. Digital signal processing and analog signal processing are subfields of signal processing. DSP includes subfields like: audio and speech signal processing, sonar and radar signal processing, sensor array processing, spectral estimation, statistical signal processing, digital image processing, signal processing for communications, control of systems, biomedical signal processing, seismic data processing, etc.
The goal of DSP is usually to measure, filter and/or compress continuous real-world analog signals. The first step is usually to convert the signal from an analog to a digital form, by sampling it using an analog-to-digital converter (ADC), which turns the analog signal into a stream of numbers. However, often, the required output signal is another analog output signal, which requires a digital-to-analog converter (DAC). Even if this process is more complex than analog processing and has a discrete value range, the application of computational power to digital signal processing allows for many advantages over analog processing in many applications, such as error detection and correction in transmission as well as data compression.[1]

3. Agency buying desks may be the most interesting piece of this ecosystem. These are the units within large media buying outfits that focus on media trading and real-time bidding.  In this space are organizations like: B3 (WPP/Group M); Adnetik (Havas Digital); Cadreon (IPG); Varick (MDC Partners); ATOM (Razorfish); VivaKi (Publicis). These groups have large amounts of client ad inventory to unload at any one time, against very specific targets, and this is where publishers need to jump in and carve out a piece of this growing RTB display ad pie. Many desks work with DSPs to facilitate real-time bidding.

4. Ad exchanges are technology platforms that facilitate the bidded buying and selling of online media advertising inventory from multiple ad networks. The approach is technology-driven as opposed to the historical approach of negotiating price on media inventory. This represents a field beyond ad networks as defined by the Interactive Advertising Bureau (IAB),[1] and by advertising trade publications Advertising Age[2], iMediaConnection[3] and ClickZ[4].
The major ad exchanges are AdECN[5], which is owned and was purchased by Microsoft in August, 2007, Right Media[6], which is owned and was purchased by Yahoo! in April 2007, ContextWeb's ADSDAQ Exchange, the leading independent exchange, and DoubleClick Ad Exchange, which is owned by DoubleClick[7], a Google subsidiary purchased in May 2007.
Ad exchanges can be useful to both buyers (advertisers and agencies) and sellers (online publishers) because of the efficiencies they provide.

5. LOTAME -
We’ve recently partnered with Lotame because they look at social media in a whole new way. Their ability to target interest groups across social media has the potential to deliver increased engagement for brand advertisers, better advertising for users, and increased monetization for sites such as Flixster. We’re excited about their offering.
Steve Polsky, President and COO, Flixster

6. As the leader in the industry, Experian® provides insights that help businesses target new markets, improve response rates and increase revenue.  We maintain extensive credit databases to help businesses lend profitably and minimize credit risk. Our collections tools improve operational efficiencies and optimize debt recovery. Our data and analytics help companies maximize their marketing investments by communicating with customers more effectively. In addition, through our expertise, we help clients protect their assets with tools and insights that help prevent fraud.