Read or open length refers to the length of time from when an individual initially opens an email until they close it.

Real-time bidding (RTB) is a means by which advertising inventory is bought and sold on a per-impression basis, via programmatic instantaneous auction, similar to financial markets.

A news aggregation website that is timely, interactive and personalised. Users submit links to blog posts, photos or videos and then other users vote those links up or down. The result is a list of the most engaging stories on the web at any given time.

A piece of software that stores data in a series of tables, with relationships defined between them. A news story might have columns for a headline, date, text, and author, where the author points to another table containing the author’s first name, last name, and email address. Information must be structured, but this allows for powerful queries. Examples include MySQL, Oracle, PostgreSQL and SQLite. Most modern websites use some kind of relational database to store content.

Renewal Bookings typically refers to the portion of bookings attributed to existing contracts.

Renewal Rate is a rate at which customers renew their plan. It is calculated by taking in consideration the number of customers who cancelled their renewal and the customers who did not cancel their renewal plan.

Rental Lists or Acquisition Lists are lists that are compiled from names obtained from a licensed third party, that has collected them from national compiled databases.

A repeat purchase is often a measure of loyalty to a brand by consumers and is often taken into account by marketing research professionals to evaluate a business.

Refers to the physical number of pixels displayed on a screen (such as 1280×1024). Unlike in print, display resolution does not refer to the number of pixels or dots per inch on a computer screen, as this can be changed by changing the resolution of the screen (which, of course, does not change the physical size of the screen). The resolution of an image, however, is often referred to in terms of pixels per inch, though this has very little effect on how the image is displayed on screen.

Retargeting, also known as remarketing, is a form of online advertising that helps to keep a brand in front of bounced traffic after they leave the website.

A list that contains the email addresses of the existing customer.

A re-posting of someone else’s Twitter post (Tweet.)

Revenue Backlog is the sum of the unrecognized revenue in the schedule of revenue over term of a SaaS or subscription agreement.

Revenue Churn is a measure of the lost revenue.

A metric for website performance calculated by dividing the total revenue by the total number of visitors to your website.

Revenue Performance Management (RPM) is a system of measuring revenue and a process that identifies and improves interactions and the customer along the revenue (sales) cycle.

Revenue recognition is an accounting principle under generally accepted accounting principles (GAAP) that determines the specific conditions under which revenue is recognized or accounted for. Generally, revenue is recognized only when a specific critical event has occurred and the amount of revenue is measurable.

A roadblock refers to an ad buy by which all ads on the page are dedicated to the advertiser. Thus, the share of voices on the page are 100%. More often, roadblocks include two ad placements and sometimes a third one.

RSS (Rich Site Summary or Really Simple Syndication) is a content delivery vehicle. An RSS Feed uses a family of standard web feed formats to publish frequently updated information such as blog posts, news articles, photos, and videos. Web applications called RSS Readers aggregate updates from multiple RSS Feeds in one location for easy viewing.

A standard for websites to push their content to readers through Web formats to create regular updates through a “feed reader” or “RSS Reader.” The symbol is generally an orange square with radiating white quarter circles. (Also see Atom)

An increasingly popular programming language known for being powerful yet easy to write with. Originally introduced in 1995 by Yukihiro “Matz” Matsumoto, Ruby has gained increasing traction since 2005 because of the Ruby on Rails development framework, which can create websites quickly. Ruby is open source and is very popular for content-based sites. Ruby on Rails A popular Web framework based on the Ruby programming language that makes common development tasks easier “out of the box.” The power of Ruby on Rails, which was developed by the Chicago-based firm 37 Signals, comes from how quickly it can be used to create a basic website.

When a website is designed and developed to work and look good on any device, regardless of screen size