There are several approaches for ESD protection of integrated circuits. This paper provides practical guidelines to I/O library designers to choose the right methodology for ESD protection of I/O libraries in advanced CMOS technologies. Guidelines are provided predominantly for low-voltage I/O libraries that are commonly used for general purpose interfaces and industrial low-voltage interfaces such as DDR, MLB, USB, etc. Additionally, some general background issues of ESD protection methodologies used in the industry are considered. This paper is focused on HBM and MM ESD protection solutions. Special CDM ESD protection solutions are not considered. (C) 2008 Elsevier Ltd. All rights reserved.