Just like auctions, account structure is often seen as one of the less sexy topics within paid search. This is a huge shame though, as how you structure your account is arguably one of the most fundamental and impactful decisions you can make while running paid search. But first:

What is an account structure?

A paid search account has various different levels of hierarchy:

• Campaigns
  ‍Campaign level is the highest level of structure within an account. While an account could have hundreds and hundreds of campaigns, most will have maybe a dozen. Campaigns will often be split by keyword theme (e.g. a clothes retailer might have one campaign for each gender, and one for children) but can be split however you like. We'll come back and look at more ways you might split out your campaigns later.‍
• Ad groups
  ‍Within each campaign are a number of different ad groups. Ad groups are often used as a more granular way to split out keyword themes. To see this, let's continue the example above of the clothes retailer. Within their men's clothing campaign they might have an ad group for men's trousers, one for men's shirts and so on.
• ‍Keywords
  ‍Within each ad group, you'll have one or more keywords. Your keywords determine what search terms you actually bid on. There are a couple of different types of keywords that we'll come to later, for now we'll just look at what are called Exact Match keywords, keywords that bid on a specific term and no others. [mens trousers] is an example of an exact match keyword, where the square brackets indicate that it's exact.‍
• Ads
  ‍Last but not least, we have ads. Ads live at the same level of the hierarchy as keywords, meaning they exist within ad groups alongside keywords. When a keyword from ad group A wins an auction, the ads which appear on the result page are chosen from ad group A. Keywords only display ads from their own ad group, never from any others. This helps control the ad copy which you show on different search terms.

We can summarise the relationships above as:

Note that one of the campaigns' ad groups have multiple keywords, while the other campaign's ad groups have only one. It's not common to see a mix of these approaches in the same campaign, which brings us to the question:

How should you structure a campaign?

If you've followed the above, you may realise that there are a couple of areas in which you can be flexible in when designing a campaign. In particular:

How many ad groups should a campaign contain?

This is the easiest question to answer, simply because it doesn't matter. Your campaign can have as few or as many ad groups if you like.

If you find yourself in a situation where you have 100s of campaigns with only a few ad groups each, it may be worth thinking about consolidating these into fewer campaigns. This doesn't have any performance benefits, it'll simply make your life easier from an admin perspective.

How many ads should an ad group contain?

To even run a campaign, your ad groups need to have at least one ad inside of them. If you don't, you don't have anything to show on all the search result auctions that you win, so what's the point?

The questions then becomes a case of whether you should have more than one ad per ad group, and the answer to this is typically yes.

Having multiple ads in an ad group allows you to test ads against each other. Testing is typically run by creating two ads which are identical to one another except for one small feature. Isolating this one feature as the difference between the ads means that you can attribute differences in performance between the ads to that feature, a process called A/B testing. We'll look in more detail about how to run A/B tests later on, I just wanted to get us in a testing mindset.

There are reasons that you might want to put more than 2 ads in an ad group. One of these reasons is to run A/B/n test, which are A/B tests with more than 2 variants. For example, if you wanted to test 3 ad variants this would be called an A/B/C test, and require 3 ads per ad group.

How many keywords should an ad group contain?

Despite its seemingly simple wording, this is perhaps one of the most contentious topics in all of paid search. The debate over it breaks down into two sides:

• Single themed ad groups (STAG)
  ‍Proponents of STAG argue that ad groups should have multiple keywords within them, and that each ad group should contain all keywords of a certain theme (e.g. 'mens trousers', to use our example from earlier).

The main argument for a STAG approach is that it makes building and management easier. Say that your campaign might has 100 keywords. Grouping them into 10 themed ad groups of 10 keywords each is arguably easier to manage than having 100 ad groups with 1 keyword each.

STAG stands in opposition to:

• Single keyword ad groups (SKAG)
  ‍Proponents of SKAG argue that each ad group should have one and only one keyword in it. For example, if your ad group is called 'mens trousers', your only keyword in it will be [mens trousers].

To understand the motivation behind SKAG, we have to remember that each keyword can only serve ads that are within the same ad group. Because there's only one keyword in a SKAG ad group, it creates a one-to-many relationship between keyword and ad group, as opposed to a many-to-many relationship as there exists within a STAG ad group.

Having a one-to-many relationship between keyword and ad group means you can tightly tailor the ad copy that gets displayed alongside each keyword, because you know those ads will show on one keyword and one keyword only.

Going back to our section on auctions, this is beneficial because it means that we can write ad copy that's highly relevant to that one keyword. This improves our ad relevance and quality scores, in turn giving us better performance in ad auctions.

Contrast this to STAG, where you have a many-to-many relationship between keywords and ads. This means that not all ads in your ad groups will be relevant to all of that ad group's ads. Some keywords will have lower ad relevance because of this, and so will incur higher costs for the same number of clicks.

This is essentially the argument for SKAG. The argument against SKAG is that while it's certainly nice to be able to tailor ad copy at a keyword level, it requires an unreasonable amount of resource and management, and isn't efficient at scale.

While I'd agree that SKAG campaigns do take more effort to build by hand, there are plenty of pieces of tech which can help with this. I'm currently working on one, called Ads Studio, which lets you build SKAG campaigns and tailored ad copy at scale.

Whichever approach you decide to take, do be conscious that your decision has implications. While I'd argue that SKAG is better for performance purposes, there are resource-driven reasons why you might want to use STAG.

Account structure: in summary

After reading the above, you should have an understanding of the basic aspects of paid search account structure. You know what what campaigns, ad groups, keywords and ads are, and how they relate to one another at a primitive level. In the next few sections, we're going to drill into these topics in more detail. To do this, we're going to start at the most basic part of the paid search hierarchy, keywords.