By understanding the theory underlying the Mechanical APDL product capabilities, you can use those capabilities more intelligently and with greater confidence while also being aware of their limitations. Studying the entire reference is unnecessary; you need only refer to specific sections as needed.
This reference does not present all theory relating to finite element analysis. If you require the theory behind the basic finite element method, many third-party sources for the topic are available. If you need theory information beyond what is presented here, consult the indicated bibliographic reference, run a simple test problem to try the feature of interest, or contact your Ansys Support Distributor for more information.