Assalaamu alaikum [peace be to you].
طاقية Taqiyah is the Arabic word for the Muslim skull cap worn by many muslim men. although there is no religious obligation to wear it, this cap has many meanings and uses:
first, it allows Muslims to recognize each other, strengthens social ties and gives a sense of group identity. especially in a non-Muslim environment.
Muslims can recognize each other instantly and this creates an immediate bond between them and they can start conversation right away as if they knew each other for a long time. this is the effect of Muslim brotherhood.
I will illustrate it in a simple example:
- Ahmed is a Muslim man taking the Metro. he sees another man next to him. he gets closer and then speaks: "Hi!" the other man looks at Ahmed and then replies "Hi!" then Ahmed asks "brother, where are you from?". the man replies "that's none of your business!"
it may not always happen like this. but it's likely to be so. when a stranger asks where are you from, you are not likely to trust them and tell them all. right?
now let's imagine the man next to Ahmed was a man with a Taqiyah and all. Ahmed would know this man is a Muslim, so he would approach him and say "Assalaamu alaikum Akhi" (Akhi means brother in Arabic). the man would reply "Wa alaikumussalaam wa rahmatullaah Akhi" (means "and peace be to you too as well and God's mercy, brother"). now an instant bond is created which makes them feel closer. Ahmed could say "so brother, where do you come from?". the man "I come from so and so." Ahmed "Oh! really! I have been there..."
without the Taquiyah and the outside look, it's not easy to spot a Muslim man. Muslim women wear the Hijab, so it's easier to recognize them. that's one of the reasons many Muslim men choose to wear the Taquiyah and grow the beard.
second, some Muslims like to wear the taqiyah imitating the behavior of the last prophet of Islam, Mohammed -peace be upon him- who used to cover his hair with a Turban. this became a habit of his followers to distinguish themselves from non-Muslims who usually left their hair exposes.
There is a wide variety of Muslims caps seen around the world. Each country or region will usually have a unique cap.
The Taqiyah is known as kopiah in Malaysia. Thakiha in the maldives, topi in Pakistan... Muslim men wear the tubeteika in Russia while in Somalia, they often wear the koofiyad...
I hope that was beneficial for you