A Service Level Agreement (SLA) is a formal contract between a service provider and a client that specifies, in measurable terms, the services the provider will furnish. It is the primary tool used to quantify the minimum acceptable quality of service. SLAs define specific metrics (Key Performance Indicators or KPIs) such as uptime, response time, and resolution time, and outline penalties or remedies for failing to meet these targets. This makes it a binding agreement that documents a common understanding about services, priorities, and responsibilities.

A. Service charter: This is a high-level public statement about the standards of service customers can expect from an organisation, not a formal, quantifiable agreement between specific parties.

B. Service guarantee: This is a specific promise about a service, with a pledge of compensation (e.g., a refund) if the promise is not met, rather than a comprehensive agreement on all service levels.

D. Service standard: This is a benchmark or a specified level of quality that a service is expected to meet. It is a component within an SLA, but it is not the agreement itself.

1. Chartered Institute of Procurement & Supply. (2018). Commercial Contracting (L4M3). CIPS Knowledge. Chapter 5

Section 5.2

"Service level agreements (SLAs)". The text explains that an SLA is a "contractual tool for managing the performance of a supplier" and details its role in defining "specific

measurable

achievable

realistic and time-bound (SMART) key performance indicators (KPIs)" to quantify service quality.

2. Lysons

K.

& Farrington

B. (2020). Procurement and Supply Chain Management (10th ed.). Pearson. In the chapter on Supplier Relationship Management

the text distinguishes SLAs as formal documents that "define the level of service to be provided" using quantifiable metrics

contrasting them with less formal service standards or guarantees. (Specific reference: Chapter 18

pp. 485-487).

3. University of Cambridge. (n.d.). Service Level Agreement (SLA) Toolkit. Information Services. Retrieved from https://www.is.cam.ac.uk/toolkit/slas. This university resource defines an SLA as "an agreement between an IT Service provider and a customer" that "describes the IT Service

documents service level targets

and specifies the responsibilities of the IT Service provider and the customer." This aligns with the definition of a quantifiable agreement.