Digital Marketing: The Ultimate Guide to Strategic Marketing

Return on ad spend is the revenue a campaign produced divided by what it cost, expressed as a ratio or a percentage: five pounds of sales for every pound of advertising is a ROAS of 5, or 500 per cent, and the number only becomes a decision once it is compared with the margin on those sales.

Digital marketing is the trade name for every commercial activity that reaches a buyer through a screen, gathered under one heading because the work is bought, delivered and counted through the same few platforms rather than because the activities resemble one another.

SEO is the work of being retrievable and worth retrieving: legible to the systems that crawl, index and select sources, and useful enough at the moment of the query that somebody still opens the page instead of accepting the answer printed above it.

Data analysis is the practice of interrogating data to answer a specific question, and of establishing how much weight the answer can bear.

Data wrangling is the work of repairing and reshaping real records, and of deciding what their gaps and inconsistencies mean, until a table can be trusted with the question being asked of it.

Data visualisation is the practice of encoding numbers as position, length and colour so that a comparison a reader would otherwise have to calculate becomes something they can simply see.