Finite element method started flourishing from 1960 or so. Since then, the method has acquired immense popularity and has found applications in various fields of engineering. Presently, the method has emerged as a powerful tool of analysis. This is because of various advantage associated with it. The method is versatile and can analyse any arbitrarily shaped structure having any combinations of boundary conditions and subjected to different types of loads. It can be used for static linear, non-linear and dynamic analysis. The method is applicable to solve problems in various fields of engineering. However, this book limits the presentation to structural engineering problems. There are two different views of looking at the finite element method. Mathematicians treat it as a method of solving differential equation. Another view, by engineers, is to treat it as a means of obtaining deformed state of structure using minimum potential energy principle.