In computing, a compiler is a computer program 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 optimised compiler for a language.

FLOW-MATIC, originally known as B-0 (Business Language version 0), was the first English-like data processing language. It was developed for the UNIVAC I at Remington Rand under Grace Hopper from 1955 to 1959, and helped shape the development of COBOL. Hopper had found that business data processing customers were uncomfortable with mathematical notation: I used to be a mathematics professor. At that time I found there were a certain number of students who could not learn mathematics. I then was charged with the job of making it easy for businessmen to use our computers. I found it was not a question of whether they could learn mathematics or not, but whether they would. […] They said, Throw those symbols out — I do not know what they mean, I have not time to learn symbols. I suggest a reply to those who would like data processing people to use mathematical symbols that they make the first attempt to teach those symbols to vice-presidents or a colonel or admiral. I assure you that I tried it.¨

COBOL (an acronym for "common business-oriented language") is a compiled English-like computer programming language designed for business use. It is an imperative, procedural and, since 2002, object-oriented language. COBOL is primarily used in business, finance, and administrative systems for companies and governments. COBOL is still widely used in applications deployed on mainframe computers, such as large-scale batch and transaction processing jobs. Many large financial institutions were developing new systems in the language as late as 2006,[9] but most programming in COBOL today is purely to maintain existing applications. Programs are being moved to new platforms, rewritten in modern languages or replaced with other software.

On September 9, 1947, a team of computer scientists and engineers reported the world's first computer bug. A bug is a flaw or glitch in a system. Thomas Edison reported “bugs” in his designs as early as the 1800s, but this was the first bug identified in a computer. Today, software bugs can impact the functioning, safety, and security of computer operating systems. “Debugging” and bug management are important parts of the computer science industry. This bug, however, was literally a bug. “First actual case of bug being found,” one of the team members wrote in the logbook. The team at Harvard University in Cambridge, Massachusetts, found that their computer, the Mark II, was delivering consistent errors. When they opened the computer's hardware, they found ... a moth. The trapped insect had disrupted the electronics of the computer. Among the team who found the first-reported computer bug was computer-language pioneer Dr. Grace Hopper. She is often given credit for reporting the bug, but that is not true. She was, however, the person who likely made the incident famous.

The Eckert-Mauchly Computer Corporation (EMCC) (March 1946 - 1950) was a computer company founded by J. Presper Eckert and John Mauchly. It was incorporated on December 22, 1947. After building the ENIAC at the University of Pennsylvania, Eckert and Mauchly formed EMCC to build new computer designs for commercial and military applications. The company was initially called the Electronic Control Company, changing its name to Eckert-Mauchly Computer Corporation when it was incorporated. In 1950, the company was sold to Remington Rand, which later merged with Sperry Corporation to become Sperry Rand, and survives today as Unisys.