There are many books and manuals about OP-AMPs covering many different topics and applications too. But this is a special book, written to understand the most common parameters that manufactures use and are detailed in the datasheet of each OP-AMP model. With an explanation about what is and the effect of each parameter in the OP-AMP behavior. So, the reader can have a more complete vision of the whole thing being able to use all the information from the manufacturer datasheet.The learning activity is also accompanied by the applications of the OP-AMPs in basic circuits: amplifier, filter, summing, integrator, differentiator, comparator, etc. In each case the most important parameters are considered as well as good techniques to make a professional design. This is done by means of a lot of details in describing the circuit and by using simple mathematical demonstration. As an additional effort the author proposes a very useful tables with summary of main formulas in each case and by selecting some of the most common OP-AMPs that can be used in almost all the applications, including recommended ones.The content of this book is separated in 4 sections: 1.OP-AMP definition and how it works.2.Description of the main parameters of the OPAMP and examples.3.OP-AMP most common applications and their analysis.4.A help-table to select an OP-AMP in applications.