Code - Code or source code is a term used to describe a written set of instructions, written using the protocols of a particular language, such as Java, C, or Python.
Expression - An expression is a legal grouping of letters, symbols, and numbers being used to represent the value of one or more variables. Expressions are highly used in a number of programming languages and many other programs, with each having its own set of legal and illegal expressions.
Algorithm - A list set of instructions, used to solve problems or perform tasks, based on the understanding of available alternatives.
Pseudocode - Pseudocode acts as an intermittent step before developing the actual code. It helps programmers prepare the organization and sequence of an algorithm.
Flowchart - A flowchart is a type of diagrammatic representation using shapes and flow lines to illustrate a computer program, an algorithm, or a process.