This is the book first-ever published to date that comprehensively and systematically addresses the major particle methods for modelling different problems in engineering and sciences. It covers different particle methods from small scales to continuum scales, with emphasis focused on three attractive and most popular meshfree particle methods: molecular dynamics, dissipative particle dynamics, and smoothed particle hydrodynamics. The book covers theoretical background, numerical techniques, code implementation, and many interesting, novel, and practical applications in 1) microfluidics and micro drop dynamics, 2) environmental and geophysical flows, 3) coast hydrodynamics and offshore engineering, and 4) high energy phenomena such as explosion and impact. Example source codes are also provided to make this book friendly and easy to read.