Topics 

Google knows that picking placements is a pain and has divided them into ‘buckets’ of placements known as topics. There are topics for all sorts of things: food, games, news, sports, etc. Google does not make it easy to understand how topics are organized unless you use Google Ads Editor. Here’s a screenshot of how topic targeting options appear in the Google Ads interface:

And here’s what they look like in Google Ads Editor:

Google will try to prompt you to select the topics it believes are most likely to give Google as much of your money as possible, but you have to sidestep those traps and hone in on the most relevant topics. Let’s say you’re looking to run ads for a local Mexican restaurant (Mexican food is my favorite). Would it be a good idea to target the ‘Food’ topic? No: it is FAR too general. Take a look at what is included in the Food topic as of June 2020 when I took this screenshot from Google Ads Editor:

Chances are you would be less than thrilled if your Mexican restaurant ads were running on websites about [INSERT IRRELEVANT TOPICS HERE]. 

Instead, I would recommend searching for ‘Mexican restaurant’ in the Google Ads interface and see what topic recommendations it prompts. Take note of the hierarchy you have to go through to arrive at a given topic, they are not organized in the most straightforward manner sometimes. Here’s one of the options I think would be a good fit:

Food & Drink > Cooking & Recipes > Cuisines > Latin American Cuisine > Mexican Cuisine

Now, cuisine and restaurants are not the same thing. Chances are that this Mexican Cuisine topic will include a lot more recipes for Mexican food than anything related to Mexican restaurants. But unless you’re going to obsessively hand-pick your placements for the rest of your display advertising career, it’s probably best to give up on the notion that you can and should control exactly where your ads show.

Display advertising is all about getting to your target market in indirect, roundabout ways. Topics are an excellent way of getting close to your target market. A general guideline of display advertising is, the more ad inventory you target, the more ad supply there is, and average costs are lower. More specific targeting typically means less ad inventory, and higher average costs.

Topics have a good deal of placements within them, but they are always going to be limited by how many people are on those placements at any given time. If nobody is looking at a given placement, there’s no one to show ads to. This is a great segue into audiences…