A technical specification is a necessary tool that helps us to define the clients´ wishes and requirements the respective individual software has to fulfill. In most cases we create a requirements specification prior to the technical specification. Another term that is equal to the technical specification is the total system specification.
The technical specification´s aim is to exactly describe which processes have to be implemented and in which way. In many cases, on the basis of this technical specification a fixed price is set.
When organizing the specification we normally use the principle of inclusion and exclusion, which means that certain cases are either explicitly included or excluded. The software´s implementation by means of the technical specification is normally followed by its approval before the system goes live. This approval is often achieved via an acceptance test.
An alternative to the technical specification is the agile software delevopment, which is a more flexible method. Although the requirements have to be clear, they do not have to be followed as strictly as in a technical specification.
Technical specifications may occur in various forms. Sometimes it is enough to have a collection of key words with several screenshots. But sometimes you need more information and the specification is similar to a book that describes all the necessary functions and aspects in detail.