Sihr and Its Types
Question

Is sihr (magic, witchcraft) real? Does it have any effect? What are the types of sihr?
Praise be to Allah.Sihr: A serious crime
Sihr is a serious crime and is one of the kinds of disbelief. It is one of the things with which people have been tested, in the past and currently, among the nations of the past, during the Jahiliyyah and in this ummah. 
The more ignorance increases, the less there is knowledge and awareness of faith, the less attention the authorities pay to this matter – the more the practitioners of sihr and trickery increase and spread in the land, to take the people’s wealth and confuse them and do other things. 
When knowledge prevails and faith increases, and the Islamic authorities are powerful, the number of these evil people shrinks and they move from one land to another, seeking a place where their falsehood will be accepted and they will be able to engage in their trickery and corruption. 
The Quran and Sunnah have described the kinds of sihr and the rulings on these matters. 
Sihr is so called because its means are hidden or secret, and because the practitioners of sihr deal with things in secret which enable them to perform illusions to confuse the people and deceive their eyes, and to cause them harm or steal their money, etc., in a secretive manner so that in most cases nobody realizes what is happening. 
Hence the last part of the night is called sahar, because at the end of the night people are unaware and they do not move about much. And the lungs are also called sahr, because they are hidden inside the body.  
Meaning of sihr
According to Sharie’ah, the meaning of sihr is what the magicians do to delude and confuse people, so that the one who is watching thinks that it is real when in fact it is not. As Allah said concerning the magicians of Pharaoh (interpretation of the meaning):
“They said: ‘O Musa! Either you throw first or we be the first to throw?’ Musa said: ‘Nay, throw you (first)!’ Then behold! their ropes and their sticks, by their magic , appeared to him as though they moved fast. So Musa conceived fear in himself. We (Allah) said: ‘Fear not! Surely, you will have the upper hand. And throw that which is in your right hand! It will swallow up that which they have made. That which they have made is only a magician’s trick, and the magician will never be successful, to whatever amount (of skill) he may attain.’” [Ta-Ha 20:65-69] 
Sihr may involve things that the magician does when tying knots on which he blows, as is referred to in the Quran (interpretation of the meaning):
“And from the evil of those who practise witchcraft when they blow in the knots.” [al-Falaq 113:4] 
And it may involve other things which they manage to do through the shayatin (devils), so they do things that may affect a man's reason or make him sick; they may cause division between a man and his wife, resulting in her looking ugly to him, or by making her hate her husband or be put off by him. This is blatant kufr as the Quran states. Allah says (interpretation of the meaning):
“They followed what the Shayatin (devils) gave out (falsely of the magic) in the lifetime of Sulayman (Solomon). Sulayman did not disbelieve, but the Shayatin (devils) disbelieved, teaching men magic.” [al-Baqarah 2:102]
 Allah informs us that they (the shayatin) committed kufr by teaching men magic. Then He says (interpretation of the meaning):
 “and such things that came down at Babylon to the two angels, Harut and Marut, but neither of these two (angels) taught anyone (such things) till they had said, ‘We are for trial, so disbelieve not (by learning this magic from us).’”[al-Baqarah 2:102]
 Then Allah says (interpretation of the meaning):
 “And from these (angels) people learn that by which they cause separation between man and his wife, but they could not thus harm anyone except by Allah’s Leave” [al-Baqarah 2:102] 
I.e., this magic and any harm that results from it is subject to the prior decree and will of Allah, for our Lord cannot be overwhelmed and nothing can happen in His Dominion against His Will. Nothing happens in this world or in the Hereafter except by His prior decree and His great wisdom, as He wills. So some people may be tested by sihr, and others may be tested by sickness, or by being killed…etc.  Allah is All-Wise in all that He wills and decrees, and in all that He prescribes for His slaves. Hence Allah says (interpretation of the meaning):
“but they could not thus harm anyone except by Allah’s Leave.” [al-Baqarah 2:102]
I.e., by His universal (kawni) will and decree, not by His legislative (shar’i) will [i.e., He wills that it should happen but He does not enjoin it and He is not pleased by such actions]. For shari’ah does not allow such things, indeed it forbids them, but by His universal leave He already knows and has already decreed that So and So will do sihr, and that So and So will be affected by sihr, just as He already knows and has already decreed that So and So will be killed, or afflicted with a certain sickness, or will die in a certain land, and will receive such and such provision, or will be rich or poor. All of that happens by the will and decree of Allah, as He says (interpretation of the meaning): 
“Verily, We have created all things with Qadar (Divine Preordainments of all things before their creation as written in the Book of Decrees, Al-Lawh Al-Mahfooz.") [al-Qamar 54:49]
 “No calamity befalls on the earth or in yourselves but it is inscribed in the Book of Decrees (Al-Lawh Al-Mahfooz) before We bring it into existence. Verily, that is easy for Allah.” [al-Hadid 57:22]
 The evils that come at the hands of the magicians or others do not happen because our Lord is ignorant, for He knows all things and nothing at all is hidden from Him, as He says (interpretation of the meaning):
“Verily, Allah is the All-Knower of everything.” [al-Anfal 8:75]
“that you may know that Allah has power over all things, and that Allâh surrounds all things in (His) Knowledge.” [al-Talaq 65:12]
So Allah knows all things, and nothing happens in His Dominion that He does not will, but He has perfect wisdom and good aims in whatever He decrees should happen to people of honour or humiliation, losing or gaining power, sickness or health, magic and other things. 
Everything that happens to people happens by the will of Allah and in accordance with His prior decree. These magicians may perform their illusions, as stated in the verse quoted above (interpretation of the meaning): 
“They said: ‘O Musa! Either you throw first or we be the first to throw?’ Musa said: ‘Nay, throw you (first)!’ Then behold! their ropes and their sticks, by their magic, appeared to him as though they moved fast.” [Ta-Ha 20:65-66]
It appeared to the onlooker as if these sticks and ropes were snakes, moving fast in the valley. They were only sticks and ropes, but the magicians, through what they had learned, made what they demonstrated before the people look different in their eyes to what it really was.
 Allah says (interpretation of the meaning):
“by their magic, appeared to him as though they moved fast.” [Ta-Ha 20:66]
And in Surah al-A’raf Allah says (interpretation of the meaning):
“He [Musa] said: ‘Throw you (first).’ So when they threw, they bewitched the eyes of the people, and struck terror into them, and they displayed a great magic.” [al-A’raf 7:116]
But in fact their sticks and ropes did not change; it was the people’s sight which changed because of the sihr, so they thought they were snakes, because of the illusion brought about by the magicians. Some people call this taqmir, which is when the magician does things to make a person not sense reality as it really is, so his eyes do not see what is really there and things may be taken from his shop or his home without him realizing it, i.e., he does not know what is really happening. So he may see a rock as a chicken or as an egg, and so on, because reality has been changed in his eyes because of the confusion wrought by the magician, and because his eyes have been bewitched. There are things that the magicians do with certain substances to make people’s eyes not see what is really happening. This is the kind of magic which Allah describes as “great” [i.e. serious, powerful] in Soorat al-A’raf (interpretation of the meaning):
“… So when they threw, they bewitched the eyes of the people, and struck terror into them, and they displayed a great magic.” [al-A’raf 7:116]
Reference: 
Majmu’ Fatawa Wa Maqalat Mutanawwi’ah by Sheikh ‘Abd Al-‘Aziz Ibn Baz, p. 65.
And Allah knows best.