Did you know that as originally conceived the web was supposed to be writable? That is, you wouldn’t just read a web page, but you’d be able to edit it, too, from right inside your browser.

You wouldn’t have needed to learn html or anything. You’d just … have written. The line between reader and publisher could blur completely. That was the plan.

We would live in a very different world today had such a thing come to pass. The entire web might have been more like Wikipedia—a large, editable hypertext. People living in wee little web villages. Instead of needing services like Blogger to set up your web pages, you would have just bought a little server space and made your own web site, merely by typing. Different programming languages might have emerged. There may never have been a Java-Script. Or maybe Netscape might have used its edge as the web platform of choice for the mid-1990s to grow into an overall work suite and taken on Microsoft across all of its products. We’d probably still have Google. But we might not have Amazon.

Amazon is a company that built its entire massive infrastructure upon a specific feature of html (the language that makes up web pages). That feature is the form—the set of buttons, dropdowns, text fields, and larger text areas that allow people to enter information into a web browser, click “submit” (a telling default), and send what they’ve entered back to some web server somewhere, where it can be stored in a database. You need forms to search. You need forms in order to give a big company your credit card. You need forms in order to set up your profile. And you need them in order to submit a book review.

Forms are everywhere. They are the part of the web where the money gets made, where the content becomes “user-generated.” Without forms the web is merely a publishing medium—a set of linked-together pages created by interested parties. With them, the web becomes the white-hot center of public discourse and the world’s largest bazaar.

The web form is, at its best, constraining. It lets you know exactly how much data to enter, and it guides the user along her way. People, when they build web pages, worry deeply over forms. There are whole books dedicated to them. There’s a culture of making them unsurprising, engaging, evocative. The forms must cry out to be filled. There are traditionally two ways to enter text in a form: the <input> element, which is typically a single line, good for capturing your name, your street address, and the like, and the <textarea>, which is longer and multi-lined. The <textarea> is where the action is, where most of our blog posts are composed, the recipient of love letters and angry comments about the president. A credit card field is a credit card field; there may be hundreds of variations, and a whole cohort of people who professionally worry themselves over making the most elegant and easy-to-use credit-card-entry systems imaginable, but they share a goal: Get the user to enter a series of digits accurately so that a transaction can occur.

What makes something easy? The elimination of steps. Reduction of cognitive load. A paucity of instructions. In the last decade the instructions started to go inside the forms; there’s even an official “placeholder” attribute for programmers to use. Now a form might have the words “What’s happening?” embedded inside of it, and when you click your mouse those words will fade but you’ll know exactly what you should be typing (what’s happening). That’s Twitter.

The more ease, the more likely it is that people will tweet their thoughts, or submit their purchases (or tweet their purchases). There are college programs in user experience, forums and conferences on making buttons irresistibly clickable. Once you make one text box you can have a million people fill it in (or a billion). Collectively we’ve made a web that is hell-bent on making more of itself, on getting people to fill in the box. Every tweet is its own little document, and every one could carry some advertising. So making it incredibly easy to tweet is one of the major movers of Twitter.

What’s remarkable is how few options we’ve had, over the years, for gathering information. The tags and tools that one can use to gather information over the web are rigid, inflexible things when you compare them to the rest of what you can do with a computer. It’s hard, for example, to build the programs used to compose music in a web browser. Or sketch a picture, or even draw a triangle. There just aren’t convenient widgets to do these things—nothing that you can reuse, built-in to every web browser in the world. The web form is mostly a textual medium: It’s still a chore, for example, to upload a picture to go with your blog posts, although some sites have made it easier. That doesn’t mean you can’t do fancy things with interaction on the web—look at Google Maps!—but the most natural thing you can do, the direction that the materials of the internet will lead you, is in capturing bits of text and making use of them.

Amazon is a good example of a company that built itself on top of simple boxes. There are many forms at Amazon. There is the big search bar. There is the checkout process. There is the form where you fill out the address of your relatives. And then there is the form that lets you write a review.

Amazon without the reviews would be just a big store. With the reviews it becomes a bizarre document of human opinion. There is a drama to reviewing, and a prioritization. First, Amazon lets you choose a star rating. You can select gold-colored stars, one to five, a completely arbitrary number that happens to correspond to the fingers of the hand. By doing this and choosing a star you have given that company an incomparable gift: You’ve expressed an opinion, presumably as a rational consumer, and you’ve done it in such a way that your thought can be converted to an integer.

This is the good stuff. When you have integers you can immediately average them. Now you have the average customer review! Amazon can classify you: This is the person who gives the single star. He really didn’t like this product. This other person, on the other hand, is a giver of five-star reviews.

Once they have acquired the all-important stars, a further tease begins. A large box appears—not huge, not screen-encompassing, but big enough for some serious analysis. “Write your review here,” it prompts. And people do. People really like reviewing things. There are at least 80 million reviews in Amazon, likely many more. Tens of millions of reviewers. And each review is a testament to the human desire to be heard. In particular, to be heard at a slightly louder volume than the branding and back-of-book promotional copy of a given item. To register delight or disgust. So they fill out the form.

The average consumer has very little fear of going on too long. Once you start typing the review, more options appear: A new box shows up; a link is there to “Add photos/video.” This is how the individual is led to part with more and more of her opinions.

It’s a new world at that moment. In the past, opinions were best kept to oneself; the role of the reviewer was serious and sanctified by the press. But the web elevated the opinion, and commercialized it. It started with seeing stars and then they asked for more of your thoughts on, whatever, toilet seats or Twilight—and hopefully it poured out of you in a way that those who come after can comprehend.

What a weird human thing to do. Like hobos leaving chalk markings. Nice lady lives here. Don’t buy this shampoo. Avoid this book if you want a happy ending. Beware mean dog. Who are we helping when we fill out that box? Mankind? Our peers? Our children? Are we just whiny babies seeking to assert some fabricated dominance, or does reviewing a product online make us part of some greater human fellowship, communicating our humanity to whatever stranger may follow along the same path?

Amazon doesn’t let you too far off the leash, of course. There’s a “tips and guidelines” style guide that tells you to “explain why you liked or disliked it” and instructs you not to “include promotional content of any kind.” This links to even further instructions on writing a “great review”—“not too short, not too long”—at least 20 words, but less than 5,000. This is an insane range. It spans everything between a tweet and a major essay in a magazine.

If you’re going to have a giant online marketplace, you need to have some ways to find the most interesting products. People will give you their opinions for free. And the engine to transmute opinions into data is the web form, so the people building your web site of necessity reach for one of those. And since computers can reproduce the same pages over and over, the forms reproduce as well, millions and billions of times, and people learn that they can fill them out and that their reviews themselves will be reviewed (thumbs up, thumbs down), forms upon forms.

As the rest of the content-driven web slowly dies off due to mergers, acquisitions, and attrition, as personal homepages vanish, as tweets and Facebook posts disappear into various kinds of ether, the product-comment remains relevant. Our web sites may decay. Our blogs may get hacked. We will all die someday. But our opinions and star ratings on Harry Potter are immortal. The online product review is the most commercially useful and long-lived content that we can make. Our fleeting opinions will outlive us all.