High- and low-level
High-level and low-level are typically terms used to classify, describe and point to specific goals of a systematic operation, though its uses also vary depending on the context - such as use in computer science versus business administration. In general, high-level is used to describe operations that are more abstract in nature, where overall goals and systemic features are typically more concerned with the wider, macro system as a whole. Alternatively, a low-level description is one that describes more specific individual components of a systematic operation, focusing on the details of rudimentary micro functions rather than macro, complex processes. Low-level classification is typically more concerned with individual components within the system and how they operate.
Differences and similarities
Due to the nature of complex systems, the high-level description will often be completely different from the low level one. For example, there are features to an ant colony that are not features of any individual ant; features of the human mind that are not known to be descriptive of individual neurons in the brain, features of oceans which are not features of any individual water molecule, and features to a human personality that are not features of any cell in a body. The descriptions of these differ depending at what level they are studied. Features which emerge only at a high level of description are known as epiphenomena.
Low-level programming language
In computer science, a low-level programming language is a programming language that provides little or no abstraction from a computer's instruction set architecture—commands or functions in the language map closely to processor instructions. Generally this refers to either machine code or assembly language. The word "low" refers to the small or nonexistent amount of abstraction between the language and machine language; because of this, low-level languages are sometimes described as being "close to the hardware." Because of the close relationship between the language and the hardware architecture programs written in low-level languages tend to be relatively non-portable.
Low-level languages can convert to machine code without a compiler or interpreter— second-generation programming languages use a simpler processor called an assembler— and the resulting code runs directly on the processor. A program written in a low-level language can be made to run very quickly, with a small memory footprint. An equivalent program in a high-level language can be less efficient and use more memory. Low-level languages are simple, but considered difficult to use, due to numerous technical details that the programmer must remember. By comparison, a high-level programming language isolates execution semantics of a computer architecture from the specification of the program, which simplifies development.
