All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
The answer to this question will be very long. You will find details in the books of Fiqh, especially those that are specifically written about Ijaarah (renting/leasing/hiring).
Nonetheless, we will provide you with a brief answer, and we say that Ijaarah means making someone own benefits or services in return for compensation, and it is divided into two types:
1 - Ijaarah of benefits (where the compensation is for the use of a benefit): such as renting houses, land, and cars.
2 - Ijaarah of labor (where the compensation is for the effort and skill of a laborer): such as hiring craftsmen, servants, and workers.
Its pillars are four:
1 - Presence of two parties (of the contract): (lessor and lessee).
2 - Offer and acceptance.
3 - Reimbursement or compensation.
4 - Benefit (specified usage).
Terms and Conditions of the contract:
There are four types of conditions:
1. Conditions for concluding the contract:
Eligibility of the two parties of the contract: each of them must be of sound mind and have reached the age of distinction.
2. Conditions of effectiveness:
The lessor who is concluding the contract must be the owner of what he is offering for hire or be the representative of the owner. So the contract of Ijaarah on something that one does not own is not effective, because he does not own the property, or if one is not the guardian of the owner; rather, the contract of Ijaarah is only concluded by the owner.
3. Conditions of validity:
A - Both parties of the contract must agree [to the subject matter of the Ijaarah].
B - The subject of the Ijaarah must be known [to both parties of the contract] in a way that does not lead to any disputes. The knowledge about the subject on what the contract is concluded should be by specifying the place of the benefit, the period of the contract should be determined, and the kind of task should be determined in regard to the contracts about labor [works and crafts].
C - The benefit on which the contract is concluded must be actually and Islamically realizable.
D - The benefit on which the contract is concluded must be lawful in Islam.
E - The compensation must be in return for money that is Islamically permissible to benefit from, and it must be known [detailed, fixed]
4. Conditions for the Ijaarah to be binding:
1 - The leased item must be free of any defect that would hinder benefitting from it. If there is any defect in the rented car (for example), the contract is invalidated.
2 - There must not be any excuse for the two parties of the contract, like if one hires a hairdresser and he [the latter] got sick.
Allah knows best.