In this textbook the author applies differential equations to physical problems, and highlights solution techniques with practical examples. Emphasis is placed on: operator methods; the convolution integral; periodic signals; the energy and power spectra; Frobenius method; Laplace, Fourier, Hankel and Z-transforms; Green's Function method; the similarity technique; the method of characteristics; the separation of variable method; and Bessel functions and Legendre polynomials. Four tables of integral transforms are also included, while exercises and answers are given on an accompanying CD-ROM.