Raspberry Pi is a credit-card-sized, single-board computer developed by the Raspberry Pi Foundation, a UK-based charity that works to ensure global access to computing and digital technology. It was initially developed as a low-cost microcomputer to impart digital skills to kids. It comes without any power supply or peripherals as it’s meant to be programmed in Python (hence, the “Pi” in its name).

Raspberry Pi (RPi) is not the only single-board computer but it’s currently the most popular. It offers several features, including:

• A powerful ARM processor
• Ethernet
• Onboard Wi-Fi and Bluetooth
• HDMI ports
• DSI display port
• CSI camera port
• Stereo audio and composite video port
• USB ports
• A 40-pin GPIO header

RPi is an all-in-one package that can be used for desktop programming, networking, web development, embedded systems programming, the Internet of things (IoT), robotics, automation — and for anything that falls within a desktop, server, or embedded domain. It can run any Debian-based Linux distribution, as well as Windows and Android.

Additionally, RPi is not limited to Python but can also take advantage of C and Java programming languages. The availability of a 40-pin, general-purpose input-output header — which includes I2C and SPI interfaces — makes it an ideal machine for embedded programming, backed by Linux (or another operating system).

RPi has truly put the power of computing into the hands of the masses by offering a cross-platform computing machine that’s extremely affordable.

What can RPi be used for?
Raspberry Pi is a low-power, general-purpose microcomputer built on a single board. The board includes its processor, GPU, RAM, and input/output peripherals. It also offers several unique hardware features that can be used for multiple applications, which are independent of any computing domain (desktop, mobile, server, or embedded), operating system, or programming language.

Since it’s possible to run any Debian-based Linux distribution on an RPi board, it can work with Linux and its internal systems, such as shell scripting or Linux system administration. The computing device can also host Windows and Android operating systems. 

Essentially, RPi is a low-cost test machine for system programming and administration. This means any programming language can be used for application development, provided it’s supported by the operating system that’s running on it. Such freedom is significant as it opens near-limitless programming possibilities for different types of apps on Raspberry Pi. Any general-purpose application on any programming language can be developed on an RPi computer.

RPi can also be used for any desktop programming task because it’s equipped with RAM, GPU, HDMI and USB ports, and a DSI display port with an onboard processor. Thanks to a 40-pin GPIO header, RPi can even connect with parallel computer bus interfaces. The additional stereo audio and composite video ports mean the board can be used to develop several multimedia applications, gaming, or a home theatre PC. The Ethernet, Bluetooth, BLE, and Wi-Fi capabilities allow for program network applications. In fact, the RPi can itself be used as a low-profile web server.

The 40-pin GPIO header (of which 28 are available) on the tiny RPi board can be used to interface sensors and actuators for embedded systems programming, robotics, and automation. The advantage of using Raspberry Pi for embedded systems: it will have an operating system running on it. This allows for complex embedded applications that may require sophisticated software. Another plus: embedded scripts or apps can be easily be upgraded or developed to upgrade when necessary via an Internet connection.

RPi can also be used for the development of Android-specific applications. Examples include cluster computing, artificial intelligence, scientific computing, supercomputing, web development, and the IoT. This is a small and powerful computer that can be used for a variety of multi-platform purposes — or until its processor hits its limit.

Operating systems
It’s possible to run any Debian-based Linux distribution on Raspberry Pi as well as Windows or Android. However, Raspbian is the official Linux distribution that’s developed and maintained by the Raspberry Pi Foundation. 

Other popular Linux distributions that can be run on RPi include Ubuntu, Kali Linux, CentOS, Arch Linux ARM, Gentoo, openSUSE, OSMC, OpenMediaVault, Recalbox, RetroPie, Lakka, and many others. 

Programming languages
Python is the primary programming language on Raspberry Pi. Scratch is another primary language available on RPi that can be used for basic computing. There is no limitation on the use of any programming language on the RPi board. Any programming language that is supported by the operating system running on it can be used for software development. Other popular programming languages that can be used on Raspberry Pi include C, C++, Java, HTML5, JavaScript, JQuery, Pearl, Erlang, etc.

Advantages
Raspberry Pi offers several benefits as a computing platform, including:

• Size: It’s a single-board computer that fits in your palm.
• Computing: The latest RPi board (RPI 4) has a 1.5-GHz Quad-core Cortex-A72 (ARM v8), 64-bit SoC that’s combined with up to 4GB LPDDR4-3200 SDRAM. Raspberry Pi 4 can also run dual displays in 4K at 60 FPS. This is a lot of computing power for a credit-card-sized computer.
• Networking: Raspberry Pi 4 has a Gigabit Ethernet port, 2.4 GHz and 5.0 GHz IEEE 802.11ac wireless (Wi-Fi), Bluetooth 5.0, and BLE. These hardware features make RPi suitable for fast Internet applications and an ideal choice for the IoT.
• Interfaces: RPi is equipped with a I2C, SPI, UART, and Xbee socket. Its GPIO pins can also be used to communicate data with other computer buses and communication protocols.
• GPU: Raspberry Pi comes with a dedicated GPU for image processing, with sufficient support for games, graphics, and 3D modeling. The board is designed with Broadcom VideoCore VI that supports OpenGL ES 3.0 graphics. RPi 4 offers two 4kp60 HDMI ports for dual displays.
• GPIO: The 40-pin GPIO header can be used to design various embedded applications. This number of GPIO pins is not available in many popular microcontroller boards. However, all of these GPIO pins are digital and there is no analog input pin.

Limitations
Raspberry Pi is ideal for most programming, learning, or prototyping, but may be insufficient for commercial applications. Certainly, RPI is capable of providing a full desktop experience, can work as an embedded computer, and is excellent for specifications. However, designing it into a product may be unwise.

One reason for this is because RPi runs an operating system on an SD card and lacks flash memory. So, its operating system is typically prone to data corruption. Certain critical features for a commercial product are also unavailable, such as a built-in ADC or RTC, which are often used in embedded systems. What’s more, RPi only has one UART and only 28 of its GPIO pins are unreserved. 

Another challenge in using RPi for commercial applications is its USB micro-connector-based power supply, which can lead to form factor and heat management issues in some applications. RPI is not equipped with reverse voltage or over-voltage protection. Its long-term availability and scalability are other concerns. Much like any computing machine, RPi also faces benchmark limitations. But it was never designed for commercial use.

Where Raspberry Pi excels is as a teacher. It’s an ideal machine to learn emerging computer technologies, programming Linux-based desktop and embedded applications, and prototyping. Note, however, that prototyping should be limited to using Linux, another operating system, or a programming language. There’s no compatible board to RPi where codes or circuits can be transferred. There are computer modules available but also have similar drawbacks.

Alternatives
Fortunately, Raspberry Pi is not the only single-board computer. Several single-board computers have similar or better specifications.
A few popular Raspberry Pi alternatives include Banana Pi M64, Pine A64, Orange Pi, Rock64 Media Board, Onion Omega2Plus, PocketBeagle, Le Potata, Odroid-C2, Rock Pi 4, Asus Tinker Board S, Beagleboard X15, etc.

Some of these boards offer on-board flash memory or embedded multi-media controller (eMMC), which make them suitable to use for commercial applications. However, these SBCs may not have as much community or development support or be as widely available as Raspberry Pi.