The word ‘Taqiyya’ is a Shia doctrine which gave its followers to conceal their religious beliefs in order to shield themselves from persecution or even death. This doctrine is only practiced by Shias who make up 20% of the world’s Muslim population.
The aim of this article is to show that ‘Taqiyya’ doctrine is part of the Shia sect only, using Muslim and non-Muslim commentaries of the doctrine of Taqiyya. This has no connection to Sunnis, who make up 80% of the World’s Muslims.
A Glossary of Islamic Terms – Aisha Bewley
Taqiya: concealment of one’s views to escape persecution. It was obligatory for the secret agents of some of the more extreme Isma’ili groups. 
The Penguin Dictionary of Islam:
Taqiyya (lit., ‘guarding oneself’) In Shiism, the practice of not openly expressing one’s faith and religious affiliation as a form of self-protection in situations of compulsion or persecution. 
Encyclopedia of Islam and the Muslim World – Richard C. Martin:
Often translated as ‘dissimulation,’ the word taqiyya is etymologically linked to piety and devotion. In twelver Shi’ite thought it has come to refer to the tactic employed by the imams (and recommended to the Shi’ites) of hiding one’s beliefs when faced with oppression. Normally, a Muslim is expected to declare his beliefs, so to deny it is a grave sin (Kabira). However, according to tradition, the shi’ite imams were faced with oppression from the sunni majority, and in order to preserve the well-being of both their followers and themselves, they dissimulated. Outwardly they would conform to Sunni belief and practice; inwardly they would remain Shi’ite. When the Abbasid caliph al-Mansur embarked on a campaign against the supporters of the sixth imam, Ja’far, the imam is said to have encouraged the shi’a to dissimulate in order to save themselves. The doctrine was based upon a certain interpretation of the Qur’anic verse 16:106, where the wrath of God is said to await the apostate ‘except those who are compelled while their hearts are firm in faith.’ This exceptive clause is interpreted in Shi’ite Qur’anic commentaries as referring to ‘those who are forced to practice taqiyya.’
Taqiyya, within the shi’ite tradition, can be seen as a balance to Shahada-the willingness to expose oneself to danger in the cause of truth. While Imam ‘Ja’far recommended taqiyya, the example of Imam Husayn seems to encourage self-sacrifice in the face of oppression. Shi’ite theologians and jurists have debated long and hard about when one should be willing to face martyrdom, and when one may resort to tawiyya. There has not emerged a unanimous orthodox position or teaching on this point, though the factors to be considered include the magnitude of the evil perpetrated by the oppressor and the estimated risk to oneself, one’s family, and the community of believers. The different tactics have been employed at a different times in Shi’ite history. The Shi’a in the Ottoman Empire, living under Sunni rule, were encouraged by some shi’ite ulema to perform taqiyya. At the beginning of revolutionary movement modern Iran, on the other hand, martyrdom was seen as virtue, and taqiyya was discouraged by some ulema. 
 A Glossary of Islamic Terms [Copyright 1418/1998 Aisha Bewley] – By Aisha Bewley, page 193
 The Penguin Dictionary of Islam By Azim Nanji, page 225
 Encyclopedia of Islam and the Muslim World [A-L] – Richard C. Martin, volume 1, page 678 – 679