Chief Minister (India)
A Chief Minister is the elected head of government of a state of India. The chief minister is the head of the state (governor is the nominal head (de jure executive)and does every thing under the guidance of the chief minister) Cabinet, and the leader of the state Legislature. By the Constitution of India, the chief minister is appointed by the Governor of the state (article 164).
The parliamentary system in India follows the Westminster system. Hence the chief ministers of the states are elected by the members of the legislature. The people do not elect the head of the government, rather they elect their representatives only. In turn their representatives select the head of the government. But once the head of the government is elected, he or she enjoys almost exclusive executive powers. This is in contrast with the head of the state, the Governor, who is the ceremonial head of state.
Selection process 
The Constitution of India sets the principle qualifications one must meet to be eligible to the office of the Chief Minister. A Chief Minister must be:
- a citizen of India
- should be a member of the state legislature. If a person is elected chief minister who is not a member of the legislature, then he/she must become a member within six months.
- of 25 years of age or more
The chief minister is elected through a majority in the state legislative assembly. This is procedurally established by the vote of confidence in the legislative assembly, as suggested by the governor of the state who is the appointing authority.
Since, according to the constitution, the chief minister is appointed by the governor, the swearing in is done before the governor of the state.
The oath of office.
I, <Name of Minister>, do swear in the name of God/solemnly affirm that I will bear true faith and allegiance to the Constitution of India as by law established, that I will uphold the sovereignty and integrity of India, that I will faithfully and conscientiously discharge my duties as a Minister for the State of <Name of the State> and that I will do right to all manner of people in accordance with the Constitution and the law without fear or favour, affection or ill-will.
— Constitution of India, Schedule 3, Para 5
The oath of secrecy
I, <Name of Minister>, do swear in the name of God/solemnly affirm that I will not directly or indirectly communicate or reveal to any person or persons any matter which shall be brought under my consideration or shall become known to me as a Minister for the State of <Name of the State> except as may be required for the due discharge of my duties as such Minister.
— Constitution of India, Schedule 3, Para 6
By Article 164 of the constitution of India, remuneration of the chief minister as well as other ministers are to be decided by the respective state legislatures. Hence this varies from state to state.
See also 
- Constitution of India, Article 173
- The Constitution of India, Article 164, Clause 5