The person who performs taqlid is termed muqallid.
The definite meaning of the term varies depending on context and age.
Sunni Islamic usage designates the unjustified conformity of one person to the teaching of another, apart from justified conformity of layperson to the teaching of mujtahid (a person who is qualified for independent reasoning).
Shia Islamic usage designates the general conformity of non-mujtahid to the teaching of mujtahid, and there is no negative connotation.
In contemporary usage, especially in the context of Islamic reformism, it is often shed in a negative light, and translated as "blind imitation".
This refers to the perceived stagnation of independent intellectual effort (ijtihad) and uncritical imitation of traditional religious interpretation by the religious establishment in general.
The term is believed to have originated from the idea of allowing oneself to be led "by the collar".
One who performs taqlid is called a muqallid, whereas one who rejects taqlid is called a ghair-muqallid.
Sheikh Shaamee Hanafi said it is "to take the statement of someone without knowing the evidence."
There are several verses (ayat) in the Quran that condemn "those who follow others blindly in matters of belief" (taqlid in matters of belief), namely 5:104-105, 17:36, 21:52-54 43:22-24.
This is interpreted as referring only to fundamentals (usul ad-din) and not to subsidiary elements (furu `ad-din) such as details of law and ritual practices that can only be learned through extensive study.
Traditionally, taqlid is lawful and obligatory when one is not qualified as a mujtahid.
Traditional Sunni scholars rely on two verses of the Qur'an, which order one to ask the people of knowledge or remembrance if they do not know and to obey Allah, the Messenger and those in authority among them.
They also rely on several hadiths including one where the Prophet Muhammad tells his companions "If one does not know what to do, the only remedy is to inquire."
They said no.
So this injured companion washed his head with water and died.
The Prophet admonished his companions by saying, "They killed him.
May Allah kill them.
If one does not know what to do, the only remedy is to inquire."
In Shia Islam, taqlid "denotes the following of the dictates of a mujtahid".
Following the Greater Occultation (al-ghaybatu 'l-kubra) in 941 CE (329 AH), the Twelver Shia are obliged to observe taqlid in their religious affairs by following the teachings of a thinker (mujtahid) or jurist (faqih).
Thus Shia who are not experts in Islamic jurisprudence (fiqh) are "legally required to follow the instructions of the expert, i.e., the mujtahid" in matters of sharia, but are forbidden to do so in "matters of belief" (usulu 'd-din).
Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Taqlid.