Digital Media Glossary

CPM is the cost an advertiser pays per thousand impressions. An impression is not necessarily a person or a viewable exposure.

Calculation: CPM = ad spend ÷ impressions × 1,000. State the currency, period and costs included.

CPC measures the average advertising cost per counted click.

Calculation: CPC = ad spend ÷ clicks. Specify whether the report counts link clicks or another click definition.

CPA is the average cost of a defined acquisition or action. A lead is not automatically a paying customer.

Calculation: CPA = ad spend ÷ counted acquisitions or actions. Identify the action, reporting period and attribution window.

From a publisher's perspective, eCPM expresses advertising earnings per thousand impressions.

Calculation: publisher eCPM = advertising earnings ÷ impressions × 1,000. An advertiser's effective cost calculation instead uses cost; label the perspective before comparing reports.

ROI compares an investment's net return with its cost.

Calculation: ROI = (return from investment − investment cost) ÷ investment cost × 100%. Define the return and costs consistently so costs are not subtracted twice. Revenue alone is not profit.

ROAS relates attributed revenue to advertising spend.

Calculation: ROAS = attributed revenue ÷ ad spend. Report it as a ratio and identify the attribution model and window. It is not the same as profit, ROI or proof of incremental sales.

An impression is a counted advertising delivery event under the platform's definition. It is a raw count, not a count of unique people, attention or clicks.

Video completion rate describes completed plays relative to a defined starting measure.

Calculation when starts are the denominator: VCR = completed plays ÷ video starts × 100%. Check the platform's definition before comparing reports; do not label completion as conversion rate.

CTR relates clicks to impressions.

Calculation: CTR = clicks ÷ impressions × 100%. The click definition and reporting period must match those used in the comparison.

Viewability indicates whether an ad met specified visibility criteria, not whether someone paid attention to it.

Google's Active View documentation describes standard display viewability as at least 50% of the ad area visible for at least one second. For display ads of 242,500 pixels or more, the threshold is at least 30% for one second. For video, at least 50% must be visible while playing for at least two seconds. Measurement eligibility matters; do not apply these criteria universally to CTV or DOOH.

Viewable rate: viewable impressions ÷ measurable impressions × 100%. Not every served impression is measurable.

Engagement rate relates specified interactions—such as likes, shares or comments—to a stated denominator.

Example definition: post engagements ÷ post impressions × 100%. Other reports use reach or followers; label the denominator rather than treating all engagement rates as equivalent. GA4 session engagement is a different metric.

A CTA is a prompt to take a particular next step, such as reading a guide or submitting an inquiry. The destination should match what the prompt asks the user to do.

In Google Analytics 4 (GA4), bounce rate is the percentage of sessions that were not engaged—not simply the percentage that viewed one page.

Google defines an engaged session as one that lasts longer than 10 seconds, includes a key event, or has at least two page or screen views.

Calculation: GA4 bounce rate = non-engaged sessions ÷ sessions × 100%. Engagement rate is the percentage of engaged sessions; the two percentages sum to 100%.

Conversion rate relates defined conversions to a specified opportunity base.

Example for a user-based rate: users who converted ÷ eligible users × 100%. Other systems use interactions or sessions; identify the platform, conversion action, denominator and period. Do not assume all reports use visitors or label video completion CVR without explanation.

DAU counts distinct users meeting a defined activity criterion during a specified day. State what qualifies as active and which time zone or rolling window applies.

MAU counts distinct users meeting a defined activity criterion during a specified month or rolling window. A calendar month and a rolling 30-day window are not the same reporting period.

ARPU expresses revenue per user for a stated period.

Calculation: period revenue ÷ the defined user base for that period. Specify whether the denominator uses active users, paying users, subscribers or an average population.

LTV estimates the value of a customer relationship over time. A revenue-based estimate differs from one based on contribution or profit.

There is no single formula appropriate to every business. State the model, retention assumptions, purchase frequency, margin, time horizon and any discounting before reporting an estimate. Match the time units when using churn or purchase frequency.

Customer churn measures the share of a starting customer base lost during a period.

Calculation: customers lost from the starting base during the period ÷ customers at the start × 100%. Netting new customers against departures would hide churn. Revenue churn is a different measure.

SEO concerns organic search discovery and visibility through content and technical improvements. It does not purchase a higher organic position. Explore SEO services.

On this site, SEM means paid search advertising. It is distinct from organic SEO. Explore paid search services.

A DSP is software used by buyers to manage digital advertising purchases across inventory sources. The available inventory and buying options depend on the platform and agreements.

An SSP is technology media owners use to manage and sell advertising inventory. It serves the supply side of the transaction, rather than replacing an advertiser's planning process.

Programmatic advertising uses software to support buying and selling digital ad inventory. Real-time bidding is one buying method; programmatic does not mean that all human decisions or negotiation disappear.

For help interpreting campaign measures together, explore reporting and analytics.