The paid media glossary.

Customer acquisition cost (CAC) is the total sales and marketing spend needed to win one new customer, found by dividing that spend over a period by the number of customers acquired in it. Paid CAC counts ad spend only; blended CAC adds tooling and team cost.

Return on ad spend (ROAS) is the revenue generated for every dollar spent on advertising, calculated as ad-attributed revenue divided by ad spend. A 4:1 ROAS means four dollars of revenue for every dollar spent. It measures revenue efficiency, not profit.

Cost per lead (CPL) is the average ad spend required to generate one lead, calculated by dividing spend by the number of leads captured. It is an early-funnel efficiency metric, and a low CPL means little if those leads never become pipeline.

Conversion rate (CVR) is the share of an audience that completed the action you were optimizing for, calculated as conversions divided by the base (clicks, sessions, or recipients). Because it is a percentage, it is only meaningful alongside the volume it was calculated on: a high rate on a small base can represent almost no conversions.

Pipeline ROAS measures ad spend against the sales pipeline it generates, the value of the opportunities created, rather than just immediate revenue or lead count. For B2B with long sales cycles, it is the truest early read on whether paid media is working.

Marginal CAC is the cost to acquire one more customer from an increase in spend, calculated as the extra spend divided by the extra customers it produced. Unlike blended CAC, which averages every customer ever acquired, marginal CAC isolates what the latest increment actually cost, which is what reveals when scaling stops being profitable.

A marketing qualified lead (MQL) has shown enough interest, such as a demo request or content download, for marketing to pass it to sales. A sales qualified lead (SQL) has been vetted by sales as a genuine opportunity worth pursuing. The gap between them is where most B2B ad budget leaks.

Multi-touch attribution distributes credit for a conversion across all the marketing touchpoints a buyer interacted with, rather than crediting only the first or last click. It is essential in B2B, where a single deal can involve many touches across weeks or months.

First-touch attribution gives 100% of the credit for a conversion to the first interaction a buyer had with you; last-touch gives it all to the final interaction before they converted. Each answers a different question: first-touch shows what creates demand, last-touch shows what closes it, and neither alone reflects a multi-step B2B journey.

Data-driven attribution (DDA) uses an account's own conversion data to distribute credit across the touchpoints on the path to conversion, rather than applying a fixed rule like first- or last-click. It is now the default conversion attribution model in Google Ads, which has deprecated the older rule-based models except last-click.

An attribution window, or lookback window, is the period after an ad interaction during which a resulting conversion is credited to that ad. Meta's default is a 7-day click window, meaning a conversion counts if the person clicked within the previous seven days; shorter windows or view-through windows credit fewer or different conversions.

Demand capture converts buyers who are already looking for a solution, for example through Search ads on category keywords. Demand generation creates awareness and interest before that search happens, for example through LinkedIn and content. You cannot capture demand that does not exist yet.

Product-market fit is the point where a product satisfies real, repeatable market demand: strangers find it, buy it, and stick with it without a personal relationship pushing the sale. In paid media it matters because ads don't create it, they expose it. Cold traffic converts only when the offer already resonates, so referrals and warm intros don't prove fit, they run on borrowed trust.

Quality Score is Google Ads' 1-to-10 rating of how relevant and useful your keywords, ads, and landing pages are. A higher score lowers your cost per click and improves ad rank, so it directly affects how far each dollar of budget stretches.

Target CPC (tCPC) is a Google Ads automated bid strategy that sets bids to get as many clicks as possible at the average cost per click you specify. It is an average, not a cap: individual clicks cost more or less, and Google aims for your target across the campaign.

Target CPA (tCPA) is a Google Ads Smart Bidding strategy where you set the average cost you are willing to pay per conversion and Google bids automatically to hit it. Set it too low and the algorithm chases only the cheapest conversions, so it acts as an optimization instruction, not a spending cap.

Performance Max (PMax) is a goal-based Google Ads campaign type that serves across all of Google's inventory, Search, Display, YouTube, Gmail, Maps, and Discover, from a single campaign. Instead of keywords, you give it assets, audience signals, and search themes, and its AI optimizes toward your conversion goal across channels.

Retargeting (also called remarketing) shows ads to people who already interacted with you, most often visitors who came to your site but didn't convert. Because the audience is already warm, it is usually far cheaper per result than prospecting, and on Google you can keep retargeting a visitor for up to 540 days.

Negative keywords are terms you exclude so your ads don't show for irrelevant searches. They protect budget from off-intent clicks, for example blocking "free", "jobs", or a competitor's brand. They can be applied at ad group, campaign, or account level, and now to Performance Max as well.

Placement exclusions (or negative placements) stop your ads from serving on specific websites, apps, app categories, YouTube channels, or videos you don't want. They are how you keep Display and Performance Max off junk inventory like games and low-quality apps. PMax respects account-level and MCC-level exclusions, but not campaign-level ones.

The Meta Pixel is a snippet of tracking code on your website that records what visitors do, so you can build retargeting audiences, measure conversions, and optimize Meta ad delivery. It is the behavioral backbone of Meta advertising, and it is increasingly paired with the Conversions API for server-side tracking.

The Conversions API (CAPI) sends conversion events to Meta directly from your server, rather than only from the browser through the Meta Pixel. It recovers measurement and optimization signal lost to browser restrictions and ad blockers, and it runs alongside the pixel, not instead of it.

The learning period is the stretch after a change while a Google Ads bid strategy recalibrates, and performance is unstable. Google documents exactly what triggers it: a new or reactivated bid strategy, a bid strategy setting change, a composition change, and some Shopping ad group target changes. Budget changes are not on that list.

Smart Bidding is Google Ads' family of automated, conversion-based bid strategies, including Target CPA, Target ROAS, Maximize conversions and Maximize conversion value. It sets bids per auction using signals you cannot bid on manually, and it needs conversion data and a calibration window to work.

Content suitability is the Google Ads account setting that controls how sensitive the content your ads can appear beside is, across YouTube, the Display Network and Google Video Partners. Its main control is inventory type: Maximum (formerly Expanded), Moderate (formerly Standard) and Limited.

Maximize clicks is a Google Ads automated bid strategy that sets bids to get as many clicks as possible within your budget. It is automated but it is not Smart Bidding: it does no auction-time bidding toward conversions, so a campaign using it will ignore your conversion goal when it bids.

Maximize conversions is a Google Ads Smart Bidding strategy that spends your budget to get as many conversions as possible, bidding at auction time using your conversion data. It asks for no target cost, which makes it the safest conversion-based strategy to start a campaign on.

The optimization event is the action you tell an ad platform to go and get: a lead, an add to cart, a purchase. It is not just a reporting choice. It is the teaching signal the algorithm uses to decide who to show your ads to, so picking one that happens too rarely leaves the system with nothing to learn from.

A significant edit is a change to a Meta ad set that sends it back into the learning phase. Meta publishes the list: any change to targeting, creative or the optimization event, adding an ad, pausing for 7 days or longer, and changing bid strategy. Budget and bid changes count only if large enough.

Learning limited is the Meta ad set status shown when an ad set is unlikely to receive around 50 optimization events in the week after your last significant edit. Delivery stays unstable and expensive until it clears the learning phase, and the usual cause is an optimization event that happens too rarely.

A targeting facet is one category of LinkedIn ad targeting, such as job seniority, job function, industry, or years of experience. The rule that trips people up: multiple values inside one facet are combined with OR and grow the audience, while separate facets are combined with AND and shrink it.

Bid cap is a Meta bid strategy that sets the maximum amount you will bid in each auction. It is a control on bidding, not on cost: Meta states a bid cap does not reflect the cost you actually end up paying, and that bid controls are not directly related to your costs.

Cost cap is a Meta bid strategy where you set the average cost per result you are aiming for, and Meta bids dynamically to get as many results as possible around that cost. Unlike a bid cap, it targets the cost outcome rather than freezing your bid at a fixed ceiling.

Customer Match is a Google Ads feature that lets you upload a list of your own customer data, usually email addresses, to build an audience from people you already know. You can use that list to target, observe, or exclude those people across Google's campaigns. Crucially, using it to exclude has no account spend requirement.

An audience exclusion tells an ad platform not to show your ads to a specific group of people. In Google Ads you can exclude audience segments, including a Customer Match list of your own disqualified leads, so budget stops being spent on people you have already decided are not worth reaching.

An A/B test (or split test) compares two versions of an ad, audience, or page that are identical except for one variable, on evenly split, non-overlapping audiences, to see which performs better. The key is a controlled, comparable split: without it, you are not measuring the variable, you are measuring the platform's delivery.

Call conversion tracking measures phone calls generated by your ads. In Google Ads it covers two separate sources: calls placed straight from an ad (a call asset or call-only ad) and calls made to a phone number on your website after an ad click. Each is set up differently, and a call is counted only if it lasts at least a minimum length you set.

A Google forwarding number is a unique phone number Google Ads assigns to route calls to your real business line while recording call details, such as duration, start time, and whether the call connected. It is the mechanism that makes phone calls measurable as conversions.

A lookalike audience is an audience the ad platform builds by taking a source list of your existing customers and finding more people who resemble them. On Meta you set its size from 1% to 20% of a country's population: 1% is the closest match to your source with the smallest reach, and larger percentages trade similarity for reach. Its quality is capped by the quality of the source list.