By definition inclusive refers to a hotel's, cruise line's, resort's or other vacation destination's including everything related to their guests vacation for one price. Items included are accommodations, food, drinks, use of recreational amenities and other activities.
Some cruise lines do not include shore excursions or any other activities that do not take place on the ship. Another exception may be alcoholic beverages, which are not included on many cruise lines and some travel destinations.
Many inclusive vacations will include three meals a day at their onboard or on-site restaurants. Access to snacks and non-traditional meal times are included with most cruises and some resort destinations.