Gathering and sharing by individuals of their health-related data to enhance their medical care or personal wellness are popular and growing rapidly. As a relatively new field, nomenclature is variable, but this is termed patient-generated health data, person-generated health data, or simply PGHD. This chapter introduces the concept of PGHD. Essential nomenclature is provided, and a model of the purpose, flow, and use of PGHD is presented and discussed. Benefits and challenges are noted, and legal, regulatory, and ethical issues are briefly outlined. Although benefits of PGHD are perceived or inherently believed, the available empirical evidence for improved and collaborative healthcare monitoring and management is slight. Also, there are many challenges. Note to the Reader: This chapter is part of the book Digital Health (ISBN: 978-0-6453320-1-8), scheduled for publication in March 2022. The book is being published by Exon Publications,