Title: Application Programming Interface (API) Author: Kriko Published: Apr 26, 2021 Last modified: Jul 11, 2026 --- 1. [Home](https://kriko.io/) / 2. [Glossary](https://kriko.io/glossary) / 3. A Letter # Application Programming Interface **(API)** An **Application Programming Interface**, commonly abbreviated as API, is a software interface that allows controlled access to specific functions of an application, service, operating system or data source. Through an API, two different systems can exchange information according to predefined rules and request-response structures. An API does not transfer all features of one application into another application. It allows authorised functions to be used through defined standards. APIs are widely used in web applications, mobile applications, operating systems, databases, libraries and cloud services. For example, a website may use APIs to display cryptocurrency prices, weather data, payment services or map features. In this process, the website sends a specific request to the relevant service, and the service returns a response in an appropriate format. This allows developers to use existing services securely and consistently instead of building every function from scratch. Flight search platforms provide a clear example of API usage. When a user selects a departure city, destination, date, passenger count and cabin class in a travel application, the system can exchange data with different airlines or travel providers. Prices, availability and flight times are retrieved from relevant providers and presented to the user in a comparative format. Platforms such as Skyscanner can combine information from many providers through these types of integrations. APIs can differ according to their access level. An **Open API**, or public API, is made available to external developers under certain rules. An **Internal API** is used only by an organisation’s own systems and teams and is not exposed to external users. Partner APIs may also be provided to selected business partners. Each API may have different terms of use, authentication methods, rate limits and data access permissions. APIs also play an important role in mobile devices. For example, when an application needs to use a phone’s camera, it relies on the camera API provided by the operating system. Location data, push notifications, fingerprint authentication and file access can also be handled through operating system APIs. This allows developers to use secure and standardised interfaces instead of interacting directly with device hardware. APIs make it easier for digital products to work together through integration. Google Maps, payment systems, social login, advertising platforms, CRM tools and data analytics services can all be connected to different applications through APIs. However, API usage is not limited to creating a technical connection. Security, authorisation, data privacy, performance, error handling and sustainable integration architecture are also essential parts of proper **API** implementation. ## Discover it in the dictionary ### URL (Uniform Resource Locator) URL stands for Uniform Resource Locator and refers to the address of a resource on the internet. It can be understood as a standard… ### Cost Per Click (CPC) CPC stands for “Cost Per Click” and refers to the cost per click in digital advertising. It is an important performance metric that shows… ### Internal Server Errors: 5xx 5xx status codes are the group of HTTP status codes that represent server-side error responses. When a user tries to access a web page… ### Agile Project Management Agile project management is an approach in which projects are divided into smaller parts and managed through continuous feedback and improvement cycles so that… ### Deep Linking Deep linking is a link structure that directs users to a specific piece of content, product, category, campaign or app screen instead of sending… ### App Store Optimization (ASO) App Store Optimization, commonly abbreviated as ASO, refers to the optimisation activities carried out to make mobile applications more visible and increase downloads in… ### Real-time Marketing Real-time marketing is a marketing approach in which brands respond quickly and contextually to current events, trends, cultural moments, user behaviour or immediate opportunities.… ### Customer Relationship Management (CRM) Customer Relationship Management, commonly abbreviated as CRM, is an approach used to manage, improve and maintain an organisation’s relationships with existing and potential customers.… ### Pagination Pagination is a web design and development method used to divide long content, product listings, comments or data sets into multiple pages. This structure… ## Track the digital heartbeat with Kriko Subscribe to receive curated insights, news, and ideas shaping the digital landscape. By checking this box, you acknowledge and accept our [privacy policy](https://kriko.io/privacy-policy).