An SLA is a Service Level Agreement. It's a contract between a company and its customers that defines the level of service the company will provide. The agreement can be between two companies, or between a company and an individual customer. The agreement should spell out what services the company will provide, how often they will be provided, and what standards the company will meet. It should also include a mechanism for measuring whether or not those standards are being met, and for resolving any problems that arise.

For businesses, SLAs can help to:

- Define the terms of service delivery

- Provide a mechanism for measuring and monitoring service performance

- Encourage customer feedback and input into service improvement plans

- Facilitate the development of new services

- Enhance customer satisfaction levels

For customers, SLAs can help to:

- Understand the terms of service delivery

- Hold businesses accountable for poor service delivery

- Provide a mechanism for challenging and seeking redress for poor service delivery

- Encourage businesses to continuously improve their services.

There are three types of Service Level Agreements (SLA):

1. Financial SLAs

2. Operational SLAs

3. IT SLAs

Financial SLAs guarantee a certain level of service for a fixed price. Operational SLAs guarantee a certain level of service in terms of uptime, response time, and so on. IT SLAs are similar to operational SLAs, but they specifically target the IT department and its services.