In theory semantic targeting means figuring out what the content on a webpage is really about and being able to place ads based on that content. For example if a website says 'sunny weather

A pixel that marks a user as belonging to a certain segment. For example an advertiser might place a segment pixel on the homepage and mark all visitors to the homepage as 'homepage visitors.'

See user data and contextual data.

A group composed of members of a target audience identified based on the webpages they visit the actions they take such as making a purchase or completing a sign-up form or data such as gender or geographical region.

Second-party data which is basically first-party data that you are getting directly from the source. You can make a deal with a particular publisher whether through your DMP or elsewhere to offer specific data points audiences or hierarchies to that other company. 

Second screen refers to smartphones or tablets used while whatching TV. The use of a second screen is a growing phenomenon and has huge potential for digital marketing traditional TV advertising and TV program promotion.

An auction type in which the bidder who submitted the highest bid pays a price equal to the second highest bid. Also known as a Vickrey auction. This auction type has been in use for over a century for the purchase and sale of a variety of goods and services and is based on game theory as applied to auction dynamics. It's a commonly used auction type in online ad trading.

SCTE-35 (ANSI/SCTE 35 2013) is a joint ANSI/Society of Cable and Telecommunications Engineers standard that describes the inline insertion of cue tones in mpeg-ts streams. The full standard name is 'Digital Program Insertion Cueing Message for Cable.'SCTE-35 is used in the US to signal a local ad insertion opportunity in the transport stream and in Europe to insert local TV programs (e.g. local news transmissions)

See real-time bidding

see Real-time bidding (RTB)

Revenue per thousand or mille impressions (mille = thousand in Latin). Related to the CPM bidding strategy.

When a single ad tag is set to send one of several different creatives. Brand and other guidelines for creative acceptance may set limits on how much creatives may vary when associated to a single tag.

Run of site. A term meaning all inventory available on a certain website.

Run of network. A term meaning all inventory managed by a network.

Return on investment. Literally how much profit is made when money is invested. ROI can also be an idiom for whether or how much a given action or risk pays off both in ad trading and business in general.