Central processing unit in the context of "Heat sink"

Computer programming or coding is the composition of sequences of instructions, called programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the application domain, details of programming languages and generic code libraries, specialized algorithms, and formal logic.

Auxiliary tasks accompanying and related to programming include analyzing requirements, testing, debugging (investigating and fixing problems), implementation of build systems, and management of derived artifacts, such as programs' machine code. While these are sometimes considered programming, often the term software development is used for this larger overall process – with the terms programming, implementation, and coding reserved for the writing and editing of code per se. Sometimes software development is known as software engineering, especially when it employs formal methods or follows an engineering design process.

In computing, machine code is data encoded and structured to control a computer's central processing unit (CPU) via its programmable interface. A computer program consists primarily of sequences of machine-code instructions. Machine code is classified as native with respect to its host CPU since it is the language that the CPU interprets directly. A software interpreter is a virtual machine that processes virtual machine code.

A machine-code instruction causes the CPU to perform a specific task such as:

In computing, a compiler is software that translates computer code written in one programming language (the source language) into another language (the target language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program.

There are many different types of compilers which produce output in different useful forms. A cross-compiler produces code for a different CPU or operating system than the one on which the cross-compiler itself runs. A bootstrap compiler is often a temporary compiler, used for compiling a more permanent or better optimized compiler for a language.

Electronic waste (or e-waste) describes discarded electrical or electronic devices. It is also commonly known as waste electrical and electronic equipment (WEEE) or end-of-life (EOL) electronics. Used electronics which are destined for refurbishment, reuse, resale, salvage recycling through material recovery, or disposal are also considered e-waste. Informal processing of e-waste in developing countries can lead to adverse human health effects and environmental pollution. The growing consumption of electronic goods due to the Digital Revolution and innovations in science and technology, such as bitcoin, has led to a global e-waste problem and hazard. The rapid exponential increase of e-waste is due to frequent new model releases and unnecessary purchases of electrical and electronic equipment (EEE), short innovation cycles and low recycling rates, and a drop in the average life span of computers.

Electronic scrap components, such as CPUs, contain potentially harmful materials such as lead, cadmium, beryllium, or brominated flame retardants. Recycling and disposal of e-waste may involve significant risk to the health of workers and their communities.

A mainframe computer, informally called a mainframe, maxicomputer, or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise resource planning, and large-scale transaction processing. A mainframe computer is large but not as large as a supercomputer and has more processing power than some other classes of computers, such as minicomputers, workstations, and personal computers. Most large-scale computer-system architectures were established in the 1960s, but they continue to evolve. Mainframe computers are often used as servers.

The term mainframe was derived from the large cabinet, called a main frame, that housed the central processing unit and main memory of early computers. Later, the term mainframe was used to distinguish high-end commercial computers from less powerful machines.

A SIM card or SIM (subscriber identity module) is an integrated circuit (IC) in the range of a 25 MHz 32 bit CPU, and 256 KB of NVM. SIMs are intended to securely store an international mobile subscriber identity (IMSI) number and its related key, which are used to identify and authenticate subscribers on mobile telephone devices (such as mobile phones, tablets, and laptops). SIMs are also able to run apps and to store arbitrary information like address book contact information, and may be protected using a PIN code to prevent unauthorized use.

These SIM cards are always used on GSM phones; for CDMA phones, they are needed only for LTE-capable handsets. SIM cards are also used in various satellite phones, smart watches, computers, or cameras. The first SIM cards were the size of credit and bank cards; sizes were reduced several times over the years, usually keeping electrical contacts the same, to fit smaller-sized devices. SIMs are transferable between different mobile devices by removing the card itself.

Computer hardware includes the physical parts of a computer, such as the central processing unit (CPU), random-access memory (RAM), motherboard, computer data storage, graphics card, sound card, and computer case. It includes external devices such as a monitor, mouse, keyboard, and speakers.

By contrast, software is a set of written instructions that can be stored and run by hardware. Hardware derived its name from the fact it is hard or rigid with respect to changes, whereas software is soft because it is easy to change.