File Types and What They Mean

In the last lesson, we covered how to obtain a computer. Now that we know what they are and how to get one, we can start looking deeper into our files and start to understand them.

When you want to see all your files, the process changes between different operating systems.

For WindowsOS, you'll click the manila folder on your Task Bar, which is typically on the lower strip along the bottom of the monitor. This will open up File Explorer. In MacOS, you'll be viewing your files through Finder. On Linux, I'll have to go over that separately.

When you open your files for the first time, it's likely their extensions, or the suffixes added to the name of a file to indicate the file's layout of data, will be hidden. There are also hidden files that you won't be able to see right away. On WindowsOS, you can show these extensions and files by going to the View Tab on File Explorer, enabling the file name extensions and hidden items checkboxes, and view the now-visible items in your folders.

(Pictured: Windows File Explorer with the View Tab open)

On MacOS, you can show the hidden files by going to the View Tab on Finder, clicking the Show Invisible Files button.

Why do we care about these? And what good do the hidden files do us? File extensions serve more than just an indication of layout - they also help operating systems determine which program to use and open those types of files. Let's go over some of the most common extensions you'll see and what they mean.

• txt

Plaintext file. This file type is for typing and when it's saved, only the characters are saved within the binary, allowing file sizes to remain extremely small.

• exe

Executable file. This file type will run a program or section of code. A lot of trojan viruses come through this way, if you're downloading from a non-reputable source. 

• jpg/jpeg

A type of image file. This file type is named after the Joint Photographic Experts Group, who invented a way to store images into a digital format based on pixels. This file type is considered a lossy image, because when it is made, data is lost in order to make the image crisp to digital screens. When you go to make these images bigger, you can see the pixels, and an image may appear jagged or blocky up close. This file would be known as a Raster File, or an image built from pixels.

• png

Another type of image file. This file type's name stands for Portable Network Graphics and was created by the PNG Development Group. They support transparency in images unlike JPGs, and when they're compressed (the process of translating image data to digital data), less data is lost than in a jpg. This file type is a favorite for designers and artists because they also allow a resolution up to 300 PPI(pixels per inch) which is perfect for print making with little to no pixels visible, creating a seamless image.

• gif

The third major image file type. GIF stands for Graphics Interchange Format and can be used for small animations and low-resolution video clips. This file type has a limited palette to work with, providing only 256 different colors, and works best with uniform colors and hard lines. There's an alternative for this file type called APNG (Animated Portable Network Graphics), which tends to be the more popular option because it supports transparency and is smaller in file size. Not only that, but they have a better range of colors and resolution because they're based in a PNG structure.

• html

HTML (Hypertext Markup Language) is the basic scripting language used by web browsers to render pages on the world wide web. This language is the building blocks for all web pages on the internet! Writing in this language to manipulate a webpage is known as web coding and development. You can also write and launch HTML files from your own machine - this will open a local copy in your web browser, which only you can see as it pulls straight from your computer rather than a server.

• css

When we code in HTML, we need to let the webpage know how to format the data we give it. Things like colors, sizes, alignment; all of this can be determined in the cascading style sheet (CSS). We'll talk more about CSS and HTML in the "HTML/CSS Basics" lesson.

• mp4

This file type is a container for Video and Audio, as well as images and subtitle information, that helps reduce file sizes. This multimedia container is a standard file type from the Moving Picture Experts Group (MPEG) and is the fourth generation of MPEG file structures. This file has different versions [.mp4 (audio and video); .m4a(audio only); .m4p(legacy iTunes file); .m4b(audiobooks/podcasts); .m4r(iPhone Ringtones); and .m4v(raw bits file or video only mp4)] based on what's in them and where it came from.

• mp3

A coding and file format for digital audio. Also known as .bit for files created before 1995.

• pdf

The Portable Document Format (PDF) is a filetype created by Adobe in 1992. Its initial creation was to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems - meaning it can be opened anywhere on any system without requiring specific programs or technology. PDFs can be editable, fillable, and interactive depending on how they're constructed.

• doc/docx

Document filetype from Microsoft's Word Processor. These files often contain more text formatting information (as well as scripts and undo information) than some other document file formats like .txt files, but are usually less widely compatible.

• xls

Spreadsheet filetype from Microsoft's Excel. A spreadsheet is an electronic document in which data is arranged in the rows and columns of a grid and can be manipulated/used in calculations.

• webp

Web Picture (webp) is an image file format developed by Google intended as a replacement for JPEG, PNG, and GIF file formats. It supports both lossy and lossless compression, as well as animation and alpha transparency. It's also really fucking annoying but you didn't hear that from me.

• mid/midi

A Musical Instrument Digital Interface file is a standardized file that connects a wide variety of electronic musical instruments, computers, and related audio devices for playing, editing, and recording music. A .midi file is not actually an audio file - it's a set of instructions, such as pitch and tempo, that are much smaller than typical audio files. A major drawback to this is the wide variation in quality of users' audio cards, and in the actual audio contained as samples or synthesized sound in the card that the MIDI data only refers to symbolically. Even a sound card that contains high-quality sampled sounds can have inconsistent quality from one sampled instrument to another.

• rar

An archive filetype contains one or more files and is compressed dramatically. This specific compression attempts to store the same data in less space through clever math. When you go to extract (or decompress) this type of file, the computer rearranges the data into its full size again. RAR (Roshal Archive) is part of WinRAR and requires the WinRAR software to extract data. Most archive file types allow password protection.

• zip

Another archive filetype to compress files together. Most modern operating systems are able to decompress and extract this file type without the need of extra software. However, zip files have multiple different encryption methods to keep their contents secure. 7-Zip, a free and open source software, tends to have a stronger encryption than most existing methods. With a strong enough password protection, they're practically impossible to open otherwise.

• tar

A Unix/Linux based archive filetype, TAR (Tape Archive) is a collection of files lumped into a singular file - also known as a tarball - and must be compressed as an additional step. Tar works well for Linux because these tarballs contain various file system parameters, such as name, timestamps, ownership, file-access permissions, and directory organization.

There are another subset of file extensions that are less common, but you may still seem them in your day to day.

• bin

A binary file is typically a filetype used to store data in the binary language. This format contains information, like images and videos from a CD/DVD. A .bin file's usage depends on how it is interpreted by the software you open it with. For instance, a bin file can display an image, while it can also serve as a firmware update for a Blu-ray player.

• iso

ISO stands for International Organization for Standardization. This international organization creates general technical and nontechnical structures to be replicated across the world. When talking about the filetype .iso, this file contains an optical disc image, or everything that would be written to an optical disc - including the file system. The way .iso files are made are through the standardization of all CDs and DVDs from ISO. This filetype is a bit outdated, but can be useful when emulating games or enjoying retro media.

• sql

A Structured Query Language (SQL) file contains statements in plaintext code that create, modify, update, and delete parts of a database.  The shortest explanation - SQL is how you get the data out of the database, using a language that the database speaks. You tell the database what data you want, where to find it, and how to define it. SQL is imperative for modern data analysis of fluctuating databases.

• apk

Android File Packages is a file format used by the Android Operating System. This file extension is useful for loading phone applications to Windows or downloading third-party apps not available to the app store.

• bmp

A Bitmap file is a large, uncompressed image file, also known as a Raw Image. This image type is great for editing and printmaking, and even for some 3D Modeling projects, but should be converted to png/jpg/etc for web uses like a website or social media.

• sys

System files are necessary Windows data for hardware or software configuration, and driver software.

• tiff/tif
  

The Tag Image File Format is ideal for high-resolution scans, such as backing up your handmade artwork and personal documents. This image filetype is popular because of its ability to be edited and re-saved without losing image quality.

• wav/wave

The Waveform Audio File Format is an uncompressed audio file typically found on Windows systems. Popular for storing original audio tracks and useful for music/audio professionals because of its size and accuracy.

• avi

Audio Video Interleave allows audio and video to play simultaneously from the same file. Legacy format created in 1992 to MP4 (which was created 2001).

• svg

Scalable Vector Graphics are images that use mathematic calculations instead of pixels to render, making them perfect for large prints like billboards or responsive web design. Usually can be created in applications like Adobe Illustrator or Clip Studio.

• js

JavaScr!pt (Spacehey doesn't like it when I write this word in a blog post) files are used to code commands and scripts for web pages, computer and phone apps, and PDFs. It has many other applications as well.

• php

These are a plain-text file that contains the source code written in the PHP [it's a recursive acronym meaning Personal Home Page(also known as a Forms Interpreter): Hypertext Preprocessor] programming language.

• csv

Comma-Separated Values are another name for spreadsheet files. These are stored as plaintext but can be uploaded into most spreadsheet programs from a CSV. This filetype is great for uploading data in alternative programs to compile and analyze things like sales or customer info.

I can't go over every filetype, but these should be the most common file extensions you'll see in the digital world. And with that, the basics of Digital Literacy have been completed! You now have the ground-level understanding of how computers work, the most common features/hardware/software of popular Operating Systems, and file extensions.

Next, we'll address your digital footprint, how it effects you, and general Internet Safety (for both for your physical and mental health, as well as your computer's health).