Lonely Planet is a travel guide book publisher. Founded in Australia in 1973, the company has printed over 150 million books.

A guide book or travel guide is "a book of information about a place designed for the use of visitors or tourists". It will usually include information about sights, accommodation, restaurants, transportation, and activities. Maps of varying detail and historical and cultural information are often included. Different kinds of guide books exist, focusing on different aspects of travel, from adventure travel to relaxation, or aimed at travelers with different incomes, or focusing on sexual orientation or types of diet.