All the Cycladian islands have maintained their spiritual aspect. This is obvious by the innumerable churches and monasteries.
Ios, an island of 108 square kilometers and less than 2000 habitants, has 365 churches (one for each day of the year). Half of them can be visited.
Ios’ churches are built in a special order (basilica with dome). This order can be seen since the era of Constantinos the Great.
Their second feature is the cross they bear. The churches of Chora bear a marble cross. The churches of the smaller villages have a stone cross. White and blue colours dominate.
The third feature is that the small space behind the sanctum is a charnel house. This is a local tradition. 
The fourth feature is that many small churches that were built during the meta-Byzantine era, have only one arch and are more solid. The sanctum always faces the East and the main entrance the West.  The bell tower is simple – mostly, it is constituted by two columns that form a triangle on the top. The dome usually has blue color, while the doors and the windows brown. A fifth feature is that most of these churches are built on ancient temples. Many of them contain pieces of ancient monuments. This adds historical and archaeological interest.

It is worth visiting the churches Panagia Gremiotissa, Panagia Katholiki, St. John, St. Aikaterini, St. Nicholas, Chrisopigi, Evangelismos, St. Nicholas at the Castle, Faneromeni, St. Irene, and many more!

Ios has many customs that have sunk into oblivion, as a result of the exponential growth of the tourist industry. However, the habitants of Ios still respect and love their traditional customs.

Some customs of the previous century are very interesting, because they reflect habits of older times.
The custom of "anegardos" revealed the agony of women to meet their future husband. Anegardos was ring that was part of their loom. When the women finished weaving a particular textile, they went out in the streets holding this ring under their arms. The first male name they would hear, would be the name of their future husband.
The custom "fotares" was dedicated to the same purpose. This was celebrated one day before Rock day. It looks like a variation of “kleidonas” one sees in other Cycladian islands. On Rock day’s eve, people light fires that must be extinguished by the unmarried women. Then, the virgins collected some ashes, put them on their heels and went home. Then all the virgins would meet above a well, and the first-born would take out some water. Then, the girls transported the water to the place where St. John (“kleidonas”) would come out. Until the virgins reach this place, the first-born should not speak. The virgins threw inside the water fruits that were marked with barley and carnations. The first-born would take these fruits out of the water. After the end of the celebration, all the women drank this water and went home. It was believed that from the moment the girls smeared the ash on their heels, until the moment they drank the water, they would hear a male name, which would be their future husband’s name.     
The custom "armypitari" also is related to marriage. The girl that would find the coin in the special pie, would marry during the same year.
All these customs and traditions are now history, as this agony about marriage no longer exists!

The customs of Easter and Christmas are very interesting. These are celebrated until today with devoutness. The most well-known habit is
"tratarisma", with the famous pasteli (sesame bar) of Ios.
    
Of course, the "panigiria" (Feasts) are always an inextricable element of the island and are celebrated with great fervor. The most famous Feast is Rock day (or Distaff Day) on 20-21 June, and is celebrated in the monastery of the Castle. Other feasts are St. John’s on 28-29 August (Kalamos monastery and Psathi), Virgin Mary’s Birth on 7-8 September (St. Theodoti and church of Panagia Palaiokastritissa). There are less important feasts like St. Barbara, Mersinia, St. George and St. Vlassis.

The traditional cuisine of Ios is the Cycladian one that is based on olive oil, pulses, seafood, cereals and vegetables. The most traditional dishes are chick-pea balls and sun-cured whitebaits (these are baked on charcoals). Tsimetia is a kind of dolma, but instead of vine leaves, cucurbit flowers are used. Caper is a favorite in salads and cooked dishes. Ios is famous for its excellent meats, thanks to the local animal husbandry (mainly goats and cattle), as well as for its cheese and dairy products.  The most well-known cheeses are the white hard salty cheese (kefalotyri), the sweet soft mizithra, and skotyri (a mixture of mizithra and aromatic herbs). Ios has great sweets. The traditional sesame bar contains thyme honey and sesame. Other sweets are the local avgokalamara, the kalasounia (fried small pies with mizithra, egg and sugar), amigdalota (almond sweets) and dried (pastota)  figs.