If a diner is running late for their reservation made through OpenTable, it is important to understand that policies may vary by restaurant. Typically, restaurants provide a grace period, often around fifteen to thirty minutes, during which they will hold the reservation. After this period, the table may be released to other guests. It is advisable for diners to notify the restaurant directly as soon as they are aware they will be late. This can help maintain the reservation and potentially offer the restaurant a chance to adjust their seating arrangements. Diners can usually find the contact information for the restaurant on the reservation confirmation email or via the OpenTable app. It is always a good practice to communicate with the restaurant, as each establishment has its own policies on late arrivals. Therefore, it is wise to be punctual to enhance the dining experience.