There is some disagreement regarding the exact definition of a low-level programming language, but all definitions share some things in common regarding the characteristics of such a computer language. Those characteristics include: similarity to binary code, required knowledge of the role of the central processing unit (CPU) and the ability of the programmer to control hardware via the language. Some people consider any computer language a low-level one if it is not similar to a language that people speak. Others consider any language that requires the programmer to understand the intricate and very complex workings of the CPU a low-level one. It should be remembered that a truly low-level programming language generally fits all of these descriptions.
Binary code, also called machine code, is the only language that the CPU, or the "brain" of a computer, understands and "speaks." Machine code, if viewed by a person, looks like many sequences of the numerals 1 and 0; they represent a state of being on or being off, much like a light that is either turned on or turned off. Code of a high-level programming language would look very different from machine code in that it contains symbols and actual words that are used in a language, usually English, that people speak. This does not mean, however, that someone who is not a computer programmer would understand the code in a high-level language any more than they would a low-level one.
Among the greatest advantages of a low-level programming language is the ability and freedom to exercise precise control over things such as memory usage and processing time. This means that programs written in a low-level language should make very efficient use of system resources, which can be highly desired when coding for systems with very limited resources. Such an advantage does not come without a price. Developers and engineers who code in a low-level programming language must have a sound understanding of the functions of the CPU in order to write instructions that affect memory and processing time.
Coding in a low-level programming language is extremely time consuming and tedious. This understandably increases the cost involved with having a program developed in such a language, because the equivalent of as little as two lines of code in a high-level language can require as many as 20 lines in a low-level programming language. Such slow development makes low-level languages primarily suited for very small programs. They are hardly ever used for the development of larger programs.