Based on a streamlined presentation of the authors' successful work Linear Systems, this textbook provides an introduction to systems theory with an emphasis on control. The material presented is broad enough to give the reader a clear picture of the dynamical behavior of linear systems as well as their advantages and limitations. Fundamental results and topics essential to linear systems theory are emphasized. The emphasis is on time-invariant systems, both continuous- and discrete-time. Key features and topics: * Notes, references, exercises, and a summary and highlights section at the end of each chapter. * Comprehensive index and answers to selected exercises at the end of the book. * Necessary mathematical background material included in an appendix. * Helpful guidelines for the reader in the preface. * Three core chapters guiding the reader to an excellent understanding of the dynamical behavior of systems. * Detailed coverage of internal and external system descriptions, including state variable, impulse response and transfer function, polynomial matrix, and fractional representations. * Explanation of stability, controllability, observability, and realizations with an emphasis on fundamental results. * Detailed discussion of state-feedback, state-estimation, and eigenvalue assignment. * Emphasis on time-invariant systems, both continuous- and discrete-time. For full coverage of time-variant systems, the reader is encouraged to refer to the companion book Linear Systems, which contains more detailed descriptions and additional material, including all the proofs of the results presented here. * Solutions manual available to instructors upon adoption of the text. A Linear Systems Primer is geared towards first-year graduate and senior undergraduate students in a typical one-semester introductory course on systems and control. It may also serve as an excellent reference or self-study guide for electrical, mechanical, chemical, and aerospace engineers, applied mathematicians, and researchers working in control, communications, and signal processing. Also by the authors: Linear Systems, ISBN 978-0-8176-4434-5.