An example of source code is someone using HTML code to create a screen.
source code - Computer Definition
Programming statements and instructions that are written by the developer. Source code is what a programmer writes, but it is not directly executable by the computer. It must be converted into machine language by compilers, assemblers or interpreters. In some cases, source code can be machine generated by programs that convert the source code of one programming language or dialect into the source code of another language or dialect. See lines of code.