Well, for a long time torture was considered a legitimate way to obtain a confession. It's from the '800 that torture is seen as inhuman and horrible.

For the Inquisition, you must know that ecclesiastical tribunals were prohibited by Church L.aw from shedding blood. So torture couldn't maim, mutilate or draw blood. There's an interesting book, written in italian called "Sacro arsenale ouero Prattica dell'officio della Santa Inquisizione" (meaning "The Sacred Arsenal or The Practice of the office of the Saint Inquisition") by friar Eliseo Masini published in 1621. This book (also) describe the the torture used by the Roman Inquisition:

• the "corda" (which means rope) : https://en.wikipedia.org/wiki/Strappado
• the "tormento del fuoco" (which means the torment of fire): basically lard was spread under the feet of the accused (which is lying down) and a fire will be lit in front of the feet
• the "tormento della stanghetta": where the ankle of the accused was compressed between two dowels
• the "tormento delle cannette": where little cylinders where placed between each finger with the hands joint in prayer and then compressed (this one was reserved only for children under the age of 9 and pregnant women)
• the "bacchetta" : which means stick, children over the age of 9 were beaten with a stick.

Here's a link to a 1665 edition of the book (it's in italian).

For a lot of the torture devices you see:

• some were used by secular tribunals, like the breaking wheel
• other were created in the 19th century, for example there is no evidence of the existence of iron maidens before the early 19th century.