What is the Islamic point of view about exaggeration and overstatement?

What is the Islamic point of view about exaggeration and overstatement?
Concise answer
Lying is considered to be one of the greater sins as it is among the indecent acts.[1] In the sayings of the Ahlul-Bayt (AS), lying has been termed as the key to sins and evils. [2] Nevertheless, there are exceptions where lying is not considered to be forbidden. One of them is exaggeration or overstatement which is characteristic of custom or common people. For instance, someone has just said something but when asked, he reacts and says, "I have said that one hundred times." Such an exaggeration is to indicate that something has been repeated many a time. It does not indicate the real number.[3] Also, there are different kinds of figurative, metaphorical and analogous speaking which are not meant for telling the truth but are allowed.[4]
If exaggeration and overstatement is not meant for concealing the truth and telling something which is untrue, there would be no problem; but if overstatement is in such a manner that it is considered to be telling a lie i.e. the audience thinks that what is told is true and they are led to take it as the truth, in such a case it is the real instance of lying and it is forbidden.

[1] Imam Khomeini, Rohullah, Sharh Chihil Hadith, p. 471, Centre for Preparation and Publication of Imam Khomeini's Works, Tehran, 52 edition, 1390.
[2] Vide: Halvani, Hussein b. Muhammad, Nuzhat al-Nazer wa Tanbih al-Khatir, p. 145, Imam Mahdi School (atf), Qom, first edition, 1408 A.H.; Cases where Lying are Permissible, question 21239; "The Consequences of Lying", question 2724.
[3] Vide: Naraqi, Mulla Muhammad Mahdi, Jami' al-Sa'adat, vol.2, p. 337 - 340, Al-A'lami, Beirut, fourth edition (without date).
[4] Ibid, p. 340.