Old-timey advertisers didn't know who would see their ads, and they also didn't really know how well they were doing. Put up an ad for soda right by a high school and maybe they'd have a rough idea of who walked by it every day, but they wouldn't know how many kids actually bought soda. It wasn't a total guessing game, but it wasn't a science, either. 

Because of this advertisers targeted different groups of people, or demographics. Teenagers, older men and women, business professionals, families, white people, black people, Asian people. Still, these groups are pretty broad. You could place an ad with a tv show that drew mostly female viewers or a radio program that had mostly teen listeners, but you couldn't get too specific. 

So ads had to be broad, too, and the products being sold were incentivised to be one sized fits all. Anything too niche for a wide audience couldn't afford to spend money on big, broad advertising.  

Since the birth of mass media, advertisers have been looking for better ways to do this, to make sure their ads hit just the right people. Enter the internet. In the early days of the internet, the ad world was still just like print or tv advertising. Ads were created to reach as broad an audience as possible.

First came display ads and like print ads they'd just sit their on your screen, and quickly advertisers tried to gussy these up - pop ups (the worst) and animated ads, everything to get attention. But the real innovation was turning ads into links.

What happens when an ad is a link? It's convenient. See an ad for a hat, click, BAM, you're at hatstore.com. But also that means hatstore.com can count how many times that link was clicked. Advertisers no longer had to estimate how many eyes saw their ads or what they did in response. And for a while, the click-through was an unstoppable measurement tool.

This brings us to the web cookie, which made these ads even stronger. Cookies are like little bread crumbs that websites and apps place on your device. They follow you around the web and report back on your habits. Suddenly advertisers could track who was clicking on those ads and where they'd go next. 

Did they browse the site, did they download a coupon, did they buy something? They could figure out who those viewers were, their shopping habits, and even what their life was like. Pre-cookie advertisers put their targets, that's you, in pretty broad demographic buckets, but now they can narrow that immensely. Ads can target just 18-24 year old women with an interest in science who live in Brazil, or 34-45 year old men who like soccer in Canada.

This is called addressable advertising, sometimes referred to as behavior targeting. Take a look around this video. Are you seeing any ads? If so, are they things you're interested in? That might be because YouTube is using cookies to display what it thinks you want to see. Your recommended videos work that way, too.

Every time you use your phone or computer you're leaving data breadcrumb trails. The websites you visit log your IP address, a unique set of numbers used to identify your computer as you browse the web. There are other kinds of unique identifiers, too. They can track what kind of device you're using, where you are, how fast your internet is, who else you follow, all kinds of stuff.

You may be thinking, 'isn't getting better music recommendations and seeing actually relevant ads worth a few cookie crumbs?' The problem is the websites and apps you do trust to use your data trails don't keep it too themselves. 

Let's take a deeper look at this in the thought bubble. When you open up a new app or website or log in to a social network, you'll often come across some terms and conditions. Sometime they're called the terms of service. These are the rules of the road.

The company is telling you what you can and can't do in the app, like use it to commit a crime or share stolen work, but they're also telling you what they will or won't do. Most of the time when we create a new account like this we just check the box to accept the terms and conditions and move on, but companies know we don't read those ridiculous documents.

Research even shows it would take us twenty-five days each year to read all the things we agree to. So more often than not we're actually consenting to a lot of stuff we probably wouldn't if we actually read the darn thing.

For example, Instagram. You think you're using an app to share photos with friends and chat with them. The app's terms of use say you can't post sexually explicit, violent, hateful, or discriminatory things on Instagram. You can't steal someone else's login, or use your account for illegal purposes. 

They have a right to kick you out if you break the rules, like spamming or threatening others or stealing someone else's photos. Okay, that makes sense, but their terms of use also say if they do want to kick you out they can do so without warning, and afterwards all of your photos and data and comments will no longer be accessible through your account.

Despite their community guidelines they say they have no official obligation to take down any Instagram content. They don't own your content, but you do grant them a "non-excluseive, fully paid and royalty-free, transferable, sub-licensable, worldwide license" to use your content. In other words they could use your photos however they want, including selling them to third parties.

Doing so would be a big breach of trust so they probably wouldn't, but they could. They use analytics tools that collect information sent by your device, including the webpages you visit, and they might use device identifiers on your phone to track your browsing habits to serve you personalized content or ads.

With Instagram or any app you use, with the right clause hidden in all that legal jargon, your info can be sold to third parties, over and over again. Then, advertisers can sell you more, better targeted ads. So when you absent-mindedly check the box to accept god-knows-what terms and conditions, you're also often signing away your right to privacy.

Right now that info mainly goes to advertisers, but you can see how our ambivalent attitude toward privacy could make us vulnerable to bad actors or, say, foreign influence on things like, you know, presidential elections. Thanks, thought bubble. 

Data tracking isn't just used to serve you personalized ads, either. It can actually determine what kind of content you see elsewhere. When we browse Amazon or Netflix they provide us with suggestions based on stuff we've already seen. These recommendation engines, in a way, are advertisements. It's showing you one show or product over another and, by extension, hiding others.

The companies that use them certainly say they're just being helpful, but these can actually limit our options and keep us boxed into the things big corporations want us to see. There are many different kinds of low-key ads, but two really common ones are easy to overlook. 

The first is sponsored content. Sponsored content can mean anything from an Instagram to a documentary that an advertiser paid to make and publish. It might now be obviously selling anything, like an article about taking care of your car, but paid for with a car company with its logo at the top. Or its that weird list of outlandish tabloid-y articles at the bottom of a more reputable site, like "You'll Never Believe How They Died!" with a picture of a celebrity who's definitely alive. 

Those are particularly hard to pick out because publishers like your favorite magazines and websites will place them alongside their own original stuff, the editorial content, so they blend in. First: learn to distinguish between ads and non-commercial information. Look for phrases like "sponsored content", "native content", "advertorial", or "presented by [brand name here]."

Celebrities and media creators may say they're partnering with a brand. That means they're getting money to promote that brand. Even when you google scope out the tiny green 'ad' in a listing that shows they paid to be at the top of the list. Second: if nothing else, remember this - when something is free, you're the product.

If you're sitting through ads to watch a video or scrolling past them on Instagram, that's the price you pay to share photos and make vlogs shipping Kate Winslet and Leonardo DiCaprio IRL.

Check through all your online profiles and see how much info you're giving away. Head to the settings on your phone and turn off geolocation features and microphone access wherever you can. And next time you create an account, think twice about handing over any personal info. Create a dummy email address for that stuff if you have to.

Finally: Know that nothing ever goes away online. Sure, the internet may forget about your embarrassing photos and snaps may disappear, but when you're online, you're being tracked. It sounds scary because it is.

The best way to navigate this hyper-targeted media environment would be to, well, log off forever. But we know you're not going to do that, that's why you're here with us today. The next best thing would be to be hyper-vigilant about what information you share online and minimize it whenever you can. Be wary of anything that seems free, because chances are you're paying for it with your attention and your life story.

Right now the biggest internet and tech companies make the rules and we all follow along because we don't like to read long legal documents. But with any new technology there are organizations and policies that try to rein in the power of big players like Facebook and Google. Sometimes they're successful, and sometimes not so much. 

We're going to learn all about that next time on Crash Course Media Literacy. Until then I'm Jay Smooth. See you.

Crash Course Media Literacy is filmed in the Dr. Cheryl C. Kinney Studio in Missoula, MT. It’s made with the help of all of these nice people, and our animation team is Thought Cafe. Crash Course is a Complexly production. If you want to keep imagining the world complexly with us check out some of our other channels, like Sexplanations, How to Adult, and Health Care Triage. 

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