What are cookies in web?

Cookies were originally short documents that carried useful information about you (the user) and your preferences when they were first formed.

Consider this: if you select a specific language on a website, the information is saved in a file called a cookie.

When you (the user) return to the website without deleting the cookie, the website will read the saved cookie and allow you to access the site in the language of your choice without having to pick it again.

Power of cookies in the web

Cookies are capable of remembering more than simply your language preferences. In reality, a cookie can hold any form of data. It can save information such as the date and time you visited a website, as well as the items you added to your shopping cart. It can also include all of the links you clicked on a certain page, akin to a web breadcrumb.

A cookie can only contain text, apart from its size, yet the possibilities are endless. What is saved to a cookie is determined by the author of the website a user visits.

Your cookies can only be read by a certain number of persons.

For example

You go to a website and choose English as your language. This is then saved to your machine as a cookie (local). If you later visit another website, the latter will be unable to read the cookie from the first. In other words, a cookie can only be accessed by the same website that saved the information.

Cookies have grown in popularity since their inception, and they have gradually evolved into a more complex yet crucial aspect of the Internet.

The quantity of data that cookies hold has increased over time.

Initially, they would only contain a few preferences, such as your chosen language and perhaps your chosen website style. However, technologists quickly discovered that the more information on you that could be stored, the better.

Data ultimately beyond their storage capacity. Developers devised a creative solution as a result.

Came up with a better Idea!!

What if they merely stored a unique ID in a cookie on your computer and kept the rest of the data in their own database?

They may be able to save a significant quantity of data this way. The cookie would merely serve as a unique identifier for your computer, allowing the website to recognise you and search its database for your information. This was the first step toward allowing third-party cookies to be used.

Only the same website that saved data to a cookie can access it later, as previously said, although one website can genuinely contain portions of another website. These bits and pieces of other websites that are integrated into the website you're visiting would be able to access cookies that they had previously saved to your computer.

Imagine visiting a website called “A”. 

In addition to their articles, many websites have advertisements. The majority of the time, these ads are made up of bits and pieces of other websites that have been embedded into the page. It's possible that the website "A" you're browsing hasn't saved any cookies on your computer and hence doesn't know anything about you. Indeed, you may visit dozens of websites that all have advertisements from the same source.

But where do the relevant ads of your interest come from? 

If a website saves a cookie on your computer, it might recognize you and save information about you on other websites as well. While reading a news website or buying online, for example, the ads on those websites can recognize you and pull up your information in their own system, dynamically showing you ads of your interest.

In general, saving information about your online activities is kinda illegal; nevertheless, the risk of our cookies is mostly decided by the ability of the website's authors to decide what information they require and, more importantly, for what purpose they use that information.

Cookies are merely a tool that can be abused, but they are intended to be utilized for the greater good. It is the people who make the cookies who are to blame.