Shani is one of the Navagrahas which are the nine primary celestial beings in Hindu astrology. Shani is embodied in the planet Saturn. Shani is the Lord of Saturday; the word Shani also denotes the seventh day or Saturday in many Indian languages.The origin of word Shani comes from "Shanaye Kramati Sa" i.e. the one who moves slowly, as Saturn takes about 30 years to orbit the Sun. Shani is also known as Shanaiscarya,Shani Bhagavan, Shaneesvara, Saneesvara, Shaneesvaran, Shani Deva.Shani is a Deva and son of Surya (the Sun God) and his wife Chhaya and hence also known as Chayyaputra. He is the cousin of Yama, the God of death. It is said that when he opened his eyes for the very first time, the sun went into an eclipse, which denotes the impact of Shani on astrological charts. He is known as the greatest teacher.Lord Shani is said to be very harmful to those who follow the path of betrayal , backstabbing and unjust revenge. He is known in Hindu scriptures as the greatest trouble giver as well as the greatest well wisher. He is depicted dark in colour, clothed in black; holding a sword, arrows and two daggers and mounted on a black vulture or a raven.

Mythology
The story of Shani's life is described in Shri Shani Mahatyam written several centuries ago. The story of Shani Mahatyam describes how devotion is required to please him and receive his blessings. Shani is described as having a dark complexion, a beautiful face, his caste is teli (Oil vendors), and he prays to Kal-bhairav. On listening to a story on the birth of Shani, Vikramaditya ridiculed him. Shani heard the remarks of Vikramaditya and cursed him. The story goes on to describe Vikramaditya's difficulties as a result of offending Shani. He loses his kingdom, he is charged with stealing, his hands and legs are cut-off by a neighbouring king. Eventually, Vikramaditya prays to Shani, who satisfied with his devotion restores his former glory.The last part of the story describes various experiences faced by various gods, demons and sages, including Brihaspati (Guru) and Shiva. Shani Mahatyam stresses values such as perseverance in difficult times, complete devotion and faith in the values one believes in, and never to lose confidence in life in spite of difficulties.Shani and HanumanThe worship of Lord Hanuman is a panacea for the malefic effects of the 'unfavourable' presence of Lord Shani. In the Ramayana, Lord Hanuman is said to have rescued Shani from the clutches of Ravana and in gratitude, Shani promised Hanuman that anyone who prayed to Him (Hanuman), especially on Saturdays, would be rescued from the "malefic" effects of Saturn, or at the very least, the effects would be softened.Another version of the encounter between Lord Hanuman and Shani is that once Shani climbed on to Hanuman's shoulder, implying that Shani's influence was beginning on Lord Hanuman. At this, Hanuman assumed a large size, and Shani was caught painfully between Hanuman's shoulders and the ceiling of the room they were in. As the pain was unbearable, Shani requested Lord Hanuman to release him, promising in return, that if a person prayed to Lord Hanuman, he (Shani) would moderate or eliminate the malefic effects of his influence on that person; following this, Lord Hanuman released Shani. 

Effects due to the position of Saturn in the horoscope 
Saturn is darkness, the enemy of light. When it is well placed in the seventh house, or well aspected, it gives its natives integrity, wisdom, spirituality, fame, patience, ability to lead, authority, long life, organizational abilities, sincerity, honesty, love of justice, awareness of right and wrong (because it rules the inner conscience), nonattachment, and asceticism.When it is not positioned or aspected favorably it brings miseries, sorrow, delay, obstruction, disappointment, disharmony, disputes, dejection, difficulties, despondency, and destruction (death). It makes its natives indisciplined, irresponsible, dishonest, dull, addicted to drugs, sadistic, greedy, lonely and afraid. Accidents, humiliation, prison, lawsuits, suicidal tendencies, fear of theft, thefts, blame, enmity, pessimism, and premature aging are also attributed to an ill-aspected or ill-posited Saturn.In the body, Saturn rules the nails, hair, teeth, bones, and nervous system .Diseases of the ears, jaundice, gout, deafness, depression, anxiety, insanity, and asthma are also connected with a Saturn that is ill-aspected or badly placed in the birth chart.Saturn is symbolic of cruelty and irritations in life for people. It is adverse in nature. It originates apprehensions of chronic diseases, accidents, enmity, financial crisis, depression of mind and retardation in business.