An API (Application Programming Interface) is the interface that lets one system communicate with another in a structured, automated way. It defines which operations are possible, which data is accepted and returned, in what format, and with what security. It is what makes it possible for an e-commerce to query stock in the ERP, for a mobile app to confirm authentication with the corporate directory, or for an external partner to send orders without human intervention.
Modern APIs are typically REST (over HTTP, JSON format), simple to consume, well supported by tools and languages. Alternatives include SOAP (legacy corporate systems, XML, more formal), GraphQL (the client chooses fields, useful for complex UIs) and gRPC (high performance, used in internal microservices). The choice depends on the case — REST remains dominant in external corporate integration.
INFOS products (MULTI, QAD, pplPortal, etc.) expose documented REST APIs for integration with external systems — e-commerce, payroll, banks, customer chains, external ATSs. The design of integrations is frequently part of the implementation project; for standard scenarios (Shopify, PHC, Primavera), pre-existing connectors speed up implementation.