Ayvalik is a seaside town in the northwest Turkey. It is a district of Balikesir province. It was alternatively called (Kidonies) by the town's formerly important Greek population although use of the name Ayvalik was widespread for centuries by both Turks and Greeks (pronounced as Ayvali by the latter).

Various archeological finds and excavations in the region prove that Ayvalik and its environs were inhabited as early as the prehistoric ages. The islets in the Ayvalik Bay (Ayvalik Körfezi) were also used for settlement purposes, together with Ayvalik, during the late Roman and early Byzantine periods. The constant threat posed by piracy in the region during the previous ages did not allow the islet settlements to grow larger and only Cunda (formerly Nesos) could maintain a higher level of habitation as it is the largest and the closest islet to the mainland. After the Byzantine period, the region came under the rule of Anatolian Turkish Beylik of Karesi in the 13th century and was later annexed to the territory of the Ottoman beylik (principality), which was to become the Ottoman Empire later. Until 1922, Ayvalik had a large Greek population. Anecdotal evidence indicates that, immediately after the defeat in the naval Battle of Chesma (Çeþme), the Ottoman admiral (later grand vizier) Cezayirli Gazi Hasan Pasha and men from the ships he could extirpate from the disaster, were lodged, on their frantic return to the capital, by a local priest in Ayvalik who did not know who they were. Hasan Pasha did not forget the kindness shown at that hour of crisis and when he became grand vizier, accorded virtual autonomy to the Greeks of Ayvalik, paving the way for its becoming an important cultural center for that community in the Ottoman Empire in the 19th century. The town was invaded by the Greek Army on 29 May 1919, and taken back three years later by Turkish Armies on 15 September 1922. After the Turkish Independence War, the Greek population in the town was replaced by a Muslim population from Greece under the 1923 agreement for the Exchange of Greek and Turkish Populations. Most of the new population that replaced the former Greek community were Muslim Turks from Mytilene, Crete and Greek Macedonia. One could still hear Greek spoken in the streets till recently. Many of the town's mosques are Greek Orthodox churches that have been converted.

Today, Ayvalik and the numerous islets encircling the bay area are popular holiday resorts. The most important and the biggest of these islets is Cunda Island (Alibey Island) which was connected to the mainland by a bridge in the late 1960s. Since September 1998, Ayvalik has had an international music academy (AIMA) which gives master classes for violin, viola and cello. It brings together students from all over the world and gives them a precious opportunity to work with distinguished masters of their branch. Ayvalik also has two of the longest sandy beaches of the whole country which extend as far as the Dikili district of Ýzmir nearly 30 km in the south. These are Sarýmsaklý and Altinova beaches. In recent years Ayvalik has also become an important point of attraction for scuba divers with its underwater fauna. Ayvalik and its environs is famous for the highly appreciated quality of olive oil production. Today, the population of Ayvalik is nearly 30,000 and much more during the summer due to its touristic importance. Ayvalik is also close to Bergama (former Pergamon) which is another important attraction for tourists with its ruins dating back to antiquity. With its rich architectural heritage, Ayvalik is a member of the Norwich-based European Association of Historic Towns and Regions.