Remember when there was only one Cookie Monster? That’s what we think every time the cookie disclaimer pops up on a website. With the ubiquity of tech, we know privacy is a major issue, but we also know that we have a very limited understanding of what cookies do. So, we called on former engineer and Klaviyo’s marketing SVP Kady Srinivasan to clear up the confusion.

Here, Kady tells us exactly what cookies are, how they work, and how they can affect our browsing habits.

So, what are cookies?
A cookie is a small text file that lives on your computer and stores/shares information with the websites you visit. They were created to help websites remember if someone had been to the website before and if so, to remember their preferences—like their favorite items or the type of content they like to read.

There are also 2 types of cookies: first-party and third-party. (When you accept cookies on a website, you generally accept both kinds.) First-party cookies are made by the website you’re visiting and are the reason you see, “Welcome back, Jane!” Third-party cookies are made by a separate website that powers an experience on the website you’re visiting. A common example is serving an ad.

Is it true that they make online shopping easier for consumers?
Shoppers are pretty high maintenance these days. We expect personalized, great experiences at every turn, and cookies are generally used to make the experience more seamless. Saving your username and password to make the sign-in process less of a hassle, offering product recommendations based on your search history, and giving discounts to loyal shoppers are a few of the ways cookies make shopping online a little easier.

What data are cookies tracking that we don’t think about?
This is where shoppers get a little creeped out. When you accept cookies from a website, you’re giving that website permission to store tiny text files on your computer. By themselves, these files can’t do anything. But when you visit a website where you accept cookies, that website can both store data on your computer and ask your computer if a specific cookie has been stored there before. (It’s important to note that third-party data is typically implicit and based on “hints” people leave as they peruse the internet, rather than declared or explicit information.)

Whether you’re checking the weather for the weekend by entering a zip code, or sharing your phone number for a discount code at your favorite boutique—if you’ve accepted cookies, this data is often stitched together to create a full user profile that includes your preferences, behaviors, actions, and interests, despite coming from a variety of sources. These user profiles can then be sold to platforms to sell hyper-targeted, personalized, high-converting ads, even though you may not have explicitly given permission for them to do so.

So, is there any harm in accepting them?
Accepting cookies has become the norm. People want that annoying pop-up window to go away, but that doesn’t mean it’s the right choice for everyone, depending on how strongly they feel about internet privacy.

Is it easy to opt-out?
Yes, but most of us don’t because we are in the instant gratification era and want to get to the content we are looking for quickly. We hit accept without really knowing what we’re agreeing to, and ultimately, people should know they have a choice when it comes to how they’re being tracked online.