Question: what is strained yogurt strained through?
About the article "Yogurt", section "Strained yogurt".

Candidate passages:
Strained yogurt contains significantly more protein than non-strained yogurt, including both casein and whey protein.
During the straining process, although the liquid whey is strained, the original whey and casein protein present in milk remain intact.
Strained yogurt, like non-strained yogurt, is also considered a good source of beneficial pro-biotics. 
Similarly, strained yogurt is widely used in Cypriot cuisine not only as an ingredient in recipes, but also on its own or as a supplement to a dish.
In Cyprus, strained yogurt is usually made from cow's milk. 
Strained yogurt, yogurt cheese, labneh ( "labanah"), or Greek yogurt is yogurt which has been strained in a cloth or paper bag or filter to remove the whey, giving a consistency between that of yogurt and cheese, while preserving yogurt's distinctive sour taste.
Like many yogurts, strained yogurt is often made from milk which has been enriched by boiling off some of the water content, and sometimes by adding extra butterfat and powdered milk.
Yogurt strained through muslin is a traditional food in the Levant, Eastern Mediterranean, Near East, and South Asia, where it is often used in cooking, as it is high enough in fat not to curdle at higher temperatures.
Dishes may be cooked or raw, and may be savoury or sweet.
Due to the straining process to remove excess whey, even non-fat varieties are rich and creamy.
In western Europe and the US, strained yogurt has become increasingly popular because it is richer in texture than unstrained yogurt, and higher in protein.
Since the straining process removes some of the lactose, strained yogurt is lower in sugar and carbohydrates than unstrained yogurt.
Most of the recent growth in the $4.1 billion yogurt industry in the United States has come from the strained yogurt segment.
"Greek-style" yogurt is similar to Greek strained yogurt, but may be thickened with thickening agents, or if made the traditional way, is based on domestic (rather than Greek) milk. 
Strained yogurt ("στραγγιστό γιαούρτι" "straggistó giaoúrti" in Greek) is used in Greek food mostly as the base for tzatziki dip and as a dessert, with honey, sour cherry syrup, or spoon sweets often served on top.
A few savoury Greek dishes use strained yogurt.
In Greece, strained yogurt, like yogurt in general, is traditionally made from sheep's milk.
More recently, cow's milk is often used, especially in industrial production. 
In south Asia (primarily Bangladesh, India, Pakistan and Sri Lanka), regular unstrained yogurt ("dahi or curd"), made from cow or water buffalo milk, it is often sold in disposable clay bowls called kulhar (Hindi-Urdu: कुल्हड़ or کلہڑ / Sinhalese: මී කිරි) .
Kept for a couple of hours in its clay pot, some of the water evaporates through the unfired clay's pores.
It also cools the curd due to evaporation.
But true strained yogurt ("chakka") is made by draining dahi in a cloth.
Shrikhand is an Indian dessert ( often eaten with poori) made with strained yogurt and sugar, saffron, cardamom, diced fruit and nuts mixed in.
It is particularly popular in the state of Gujarat and Maharashtra, where dairy producers market shrikhand similar to ice cream.
In Pashtun-dominated regions of Pakistan a strained yogurt known as "chaka" is often consumed with rice and meat dishes.