The emergence of Web 2.0 and social media has led to an increase in the number of consumers using them to search for information about products and services and to carry out transactions. The purpose of the paper is to explore the extent to which Greek consumers use online travel review sites (TripAdvisor, Booking.com, social media, etc.) in three phases of their trip: before the trip, during the trip, and after the trip. The objective is to investigate the extent to which the choices and bookings made by Greeks before and during their trip in hotels, restaurants, etc. are influenced by comments, ratings, and reviews posted by other users on the internet. In order to meet this purpose, a survey was conducted via a structured self-completed questionnaire in a sample of 332 people in Greece. The study’s results revealed that Greeks are heavy Internet and social media users. The vast majority of them, before buying tourism products and services, seek and read comments, reviews and ratings of other users on the internet, especially in the pre-travel phase. These reviews concern different tourism businesses, mainly hotels, restaurants, airlines, but also tourist destinations and attractions. For these searches they mainly use popular platforms, such as TripAdvisor, Booking.com, and Google. Participants consider that tourism services, due to their intangible nature, involve a high degree of risk, and they do not trust advertisements as they often prove to be misleading. However, most agree that the freedom of speech and expression that exists online can allow the dissemination of unverified, malicious, derous, or distorted information about a tourism business or destination. The results of the research provide useful implications for tourism businesses and organizations on how to manage online reviews in order to enhance their online image and protect their reputation.