Orhan is often referred to as sultan, but this title was not introduced in the empire until 1394.
Orhan was son of the first bey, Osman 1.
During the reign of Orhan, the successes of him and his preceeding father against Byzantium, proved attractive to Muslim warriors from other tribes. Hence his ghazi army grew, and proved to be most effective facing the Byzanine troops.
During his reign some elements of the new state was consolidated. Minting of coins as well as building of mosques, schools, and trade centres in conquered towns proved that this new ruler was building a state, and not just razing weak conquered lands.

BIOGRAPHY
1288: Born as son of Osman, the heir as leader of the Kayi branch of the Oguz Turkmen. His father would become the founder of the Ottoman Empire few years after that again.
Around 1324: At bey Osman's death, Orhan becomes new bey.
1327: Silver coins are minted in Orhan's name.
1331: Captures the city of Nicaea, which was renamed to Iznik.
1337: Captures Nicomedia, which is renamed to Izmit.
1345: Annexes the principality of Karasi, which gave him control over the horthwestern corner of Anatolia.
1346: The Ottomans become ally of the the pretender for emperor of the Byzantine Empire, John 6 Cantacuzenus, and help him against his rival John 5 Palaeologus.
— Orhan marries John's daughter Theodora, and he receives the right to conduct raids in the Balkans.
1354: Gallipoli is seized, and will become an Ottoman foothold in Europe.
1360: Dies, and the power of the empire passes over to his son, Murad 1.

Ottoman Empire