If you enter the world of digital marketing, you’re likely to hear cookies, pixels, and tags talked about nonstop. To a developer, there’s a world of difference between two out of the three. To the rest of us common folk, they’re all one and the same.
What is a cookie?
Before we get into cookies, you need to understand what a web server is. A server is a computer that delivers data to your computer. A web server delivers websites. An ad server delivers advertisements. Simple enough. So how do cookies relate to web servers?
A cookie is a piece of code placed on your browser by a web server. Because you visited that website of your own volition, it’s called a first-party cookie. You technically agreed to these terms and conditions allowing the cookie on your browser whenever you first visited the website. Nowadays with stricter privacy laws in Europe, websites have to make it more obvious that they’re using cookies and that you agree to those terms and conditions.
The cookie a web server places on your browser can store different types of information, but the basic premise is to identify a) you and b) the website you visited that placed the cookie to begin with.
Examples of cookies in everyday life:
- You go to Pinterest and you’re already logged in
- Web analytics programs know if you’re a new or returning user
- You visit a website for shoes and those same shoes follow you around to different websites (they market to you again, thus this is called remarketing)
What is a pixel?
Sometimes servers do talk. Other times they don’t talk. That’s where pixels come in. You wouldn’t want to dump all your digital advertising data into your Google Analytics data and vice versa (maybe you would, but I don’t think either company would agree to that), but you would want them to at least try and communicate and pass little bits of data back and forth.
For example, if someone saw your ad on a news website and then purchased an item on your website, you’d want to know that so you’d have more ads that do exactly that same thing. However the fact that someone made a purchase on your website can’t be sent directly to the ad program because the two servers don’t talk. To get around this, developers created the pixel.
Remember when you took a picture back in the day and it was really pixelated? As in you could really see those squares? A modern-day advertising pixel is the same thing as an old pixel – a minute area of illumination on a display screen. These modern pixels are most often transparent. When they are placed on the website, only advertisers and websites know they’re there. Whenever your browser downloads a page or an email, this pixel downloads too, just like any other image.
The pixels then send the cookie to the server when a user completes the action you want them to – whether it’s making a purchase, filling out a form, or finding a location. Depending on the pixel, the action may be as simple as viewing the page. We need the pixels because the web server and the ad server don’t talk to each other.
What is a tag?
Tags are the keywords used to describe an element on the page and all their attributes. A pixel tag is just that – an element on the page and all of the attributes relating to that pixel. To that end, sometimes the word tags and pixels are used interchangeably.
A pixel is always going to be a tag, but a tag isn’t always going to be a pixel. For more information on tags, check out my blog all about anchor tags and anchor tag IDs, coming next week.
A Real Life Example of a Cookie, a Pixel and a Tag
Let’s go back to the topic of remarketing for our real life example. Everyone at one point or another has had a pair of shoes follow them around from website to website. So why does this happen?
First, an ad platform has purchased real estate on multiple websites. Secondly, a company, let’s say William’s Shoe Store, buys some real estate from the ad platform. While William could buy the real estate directly from another website, most likely it would be more costly and William doesn’t have the technology himself to track it.
Now let’s say you visit William’s Shoe Store website. First off, William is likely going to place a cookie on your computer for basic web tracking. This cookie won’t talk to his ad platform, but he needs it for web tracking nonetheless. William also has a pixel on his website. This pixel is given to him by the ad platform. This ad platform has a server (an ad server) that also sets a cookie on your computer. They now know you visited William’s website.
Remember, the ad server that placed the cookie on your computer has access to all the other websites that sold real estate to the ad platform. Which means that when William bought some ad space from that ad platform, it’s likely the ad for his shoe store will show up on your computer. Specifically, his ad will show up because he told the ad platform he wanted to retarget people that visited his website before. All of which the ad platform knows because of the cookie they placed on your website through the pixel William placed on his website.
Summary
Cookies, pixels, and tags are all related, but there are key differences that separate the three elements. The biggest difference between a cookie and a pixel is who is trying to track you – a third party ad tool or the website itself. At the end of the day though, they’re all meant to capture information about users to deliver a more customized web experience.
Looking to learn how to implement tags and pixels without the use of a developer? Read my post about Google Tag Manager.