Have you opened a PDF this week? Chances are you work with them regularly. Despite some other file types fading into obscurity, PDFs are still a popular choice (despite Adobe Reader becoming unnecessary).

Have you ever wondered why this is? Let's explore how PDFs work, why they're important, and the reasons they still enjoy so much popularity.

The History of PDF

PDF stands for Portable Document Format. Created by Adobe, it first launched in the early 1990s as a way to completely store a document in one file. Because the web was young when PDF was growing, they were mainly used for desktop publishing of documents to print. Companies used PDFs to save posters, flyers, and other similar types of files for physical printing.

It took PDFs a while to get going. Adobe Acrobat wasn't easy to get hold of, PDFs didn't have all the integration features they do today, and using dial-up to download a large PDF was painfully slow. After a few years, Adobe released Adobe Reader free for all, and the PDF eventually beat out several competitors to become the file standard for fixed documents.

Interestingly, PDF was originally a proprietary format, meaning that Adobe controlled PDFs and how they functioned. In 2008, they dropped this ownership and the PDF became an open standard. Now PDFs still have a basic set of properties, but these are independent of Adobe. Indeed, you can find dozens of other free PDF readers.

How PDFs Work

To see why the PDF was such a revolution when it arrived, we must understand what the standard was at the time. In the early 90s, professional software used to create graphics and documents resulted in unbearably large files, especially when they had pictures, fonts, and other graphical elements embedded. Remember that machines in this time had a tiny fraction of the processing power of the computer you're using, meaning every bit of efficiency was vital.

In an attempt to fix this, software developers started using links to other resources on the computer. Say you used a special font in your document. Instead of saving all the data for this font inside your document, it would pull the needed information from the font's installation folder on your computer. This reduced the load on the document file, making it lighter.

This would work fine as long as you didn't move the font on your computer. However, if you brought the file to a different computer that didn't have your particular font installed, it wouldn't look right. You can imagine the pain of spending all that time creating an important document and then having it look awful because you didn't keep the links to graphical elements alive.

The PDF changed this. Adobe found a way to gather all the parts of a file and make it into a smaller whole. Obviously, this is a much more efficient way than the workarounds that developers used before PDF was around.

And that's why PDFs became the standard.

Why They're Important

The portable in PDF is significant: PDFs look the same no matter what device they're viewed on. Whether you're using Windows 10, a Mac, Chrome OS, Android, Windows Phone, an iPad, or Windows XP -- on any software and hardware, PDFs stay consistent. The information contained in a PDF is not dependent on the creator's or the viewer's device. Including fonts, pictures, charts, and the like is no struggle for a PDF.

Compare this to sending a Microsoft Word document to someone. What happens if your recipient doesn't have Microsoft Word on their computer? Sure, they could open it in Google Docs, but it might look a lot different since Docs renders files differently. If you spent a lot of time getting tables, images, and other elements just right, it might all go out the window. And what if they try to open the Word document on their phone?

As a general rule, PDFs are meant for viewing. What you see when you press Save is what anyone else that views the document will get. And you don't even have to have a reader installed -- most modern browsers open PDFs with no problem. While you can edit PDFs, you're limited to few options for free unless you pay up for premium software like Adobe Acrobat, Foxit PhantomPDF, or Nitro.

In addition to the portability described above, PDFs carry several features that have contributed to their continued popularity.

For one, PDFs allow for fine-tuned security settings. When you create a PDF, you can disable viewers' ability to print the document, leave comments on it, or copy its text. Thus, when governments and businesses put forms online, they can heavily restrict them to prevent abuse. For more security, you can also password-protect a PDF.

You've likely noticed that PDFs also work with fillable fields. A PDF creator can place highlighted blocks anywhere in a document to show where they'd like a signer to add information. Even if they've restricted editing, a viewer can still type their name, address, and other pertinent info into these fields. PDFs support electronic signing, so you can add your consent to a document without having to print it out.

Minor features like adding comments, highlighting, stamps, plus hyperlinks and other live content have kept PDFs relevant into the current decade. Optical recognition software can capture documents and easily turn them into PDFs, and some independent publishers even put out books as PDFs. Its ease of use, solid feature set, and ubiquity has enshrined the PDF into everyday computing life.

What Did You Learn About PDFs?

We've taken a brief survey of the PDF to find out how it got started, how it works, and what makes it so important and popular. In a world with varying operating systems, screen sizes, browsers, and hardware components, the PDF stands firm and unchanging. Knowing that the document you created won't go through any weird changes before your viewer sees it is comforting. That's what the PDF provides, and thus it's been the standard for over two decades.

Now that you know all about PDFs, find out the best ways to share them online!

How often do you use PDFs? Do you have another reason for using them other than those listed here? Let us know what you think about this file format in the comments!