Taqiyya is the act of hiding one’s religious belief in front of fanatic and obstinate opposites when there may be possibility of a danger to that person.
For example when an Unitarian Muslim trapped among obstinate infidels, and if he express his belief maybe those infidels kill him, hurt him hard, wring his money or even aggress his family, then he hides his belief to save himself and his belongings.
Or if a Shi’aa caught in the middle of desert by an extremist Wahhabi who thinks killing a Shi’aa is allowed, then he hides his belief for saving his life, his assets and his family.
Any wise person confirms that this is a wise and completely logical act, because nobody should give over his/her life due to fanaticism of fanatics.