A process may be defined as a series of actions that is performed in order to achieve a result. Process description means writing about how something is made or how something happens. It includes a step by step description of a process in an organised manner.
The goal of writing a process description is to provide a general introduction to how something works. The introductory paragraph introduces the topic of description and gives concise details about the subject. The paragraphs in continuation add to the theme of the introductory paragraph and the concluding paragraph winds up the process description.
Process descriptions avoid giving commands, avoid using the pronoun "you," and make use of the present tense. In process description, words such as firstly, then, next, finally etc. are used. Passive voice is generally used while describing a process.