Words, explained

Of everybody who saw it, the share who clicked it.

A hundred people see your banner, three click it, that is a 3% click-through rate. It is how you compare two things fairly: a headline that gets twice the clicks from the same number of viewers is simply better, and no amount of liking the other one changes that.

Somebody did the thing you wanted them to do.

It does not always mean a sale. On an opt-in page a conversion is an email address. On a sales page it is a purchase. Always ask what somebody means by it when they quote you a number, because "20% conversion" is extraordinary for a sale and ordinary for an opt-in.

One showing of your advert to one person.

Not a click and not a visit - just the fact that it was displayed. Useful mainly as the bottom half of a click-through rate. A thousand impressions means nothing on its own; a thousand impressions and forty clicks tells you something.

The share of people who opened your email.

Driven almost entirely by two things: whether they recognise your name, and whether the subject line made them curious. It has become a rougher measure than it used to be, because some mail apps now open images automatically and register an open that never happened. Watch the trend rather than the exact number.

A link that counts its own clicks, so you know which advert actually worked.

Run a different tracking link in each place you advertise and the numbers tell you where to spend your time. Without them you are guessing, and guessing usually means carrying on with the thing that feels like it is working.

One person, counted once, no matter how many times they come back today.

Worth checking which number somebody is quoting you. A page with 1,000 views and 200 unique visitors is a page 200 people looked at five times, which is a different story from 1,000 people glancing once.