An offer letter is a formal document provided by an employer to a selected candidate, officially extending a job offer. It includes key details such as the job title, start date, salary, work hours, job location, and any benefits. The letter outlines the terms and conditions of employment, such as probation period, reporting structure, and job responsibilities. It also specifies any contingencies, like background checks. The offer letter is signed by a company representative and often requires the candidate's signature to confirm acceptance, serving as a binding agreement once accepted.