An API is a way for programs to agree on how to communicate. One sends a request; the other checks it, performs an authorized action, and returns a result.
For example, an online shop sends an order to a CRM. The CRM creates a task for a sales manager. A delivery service returns a tracking number. All of this happens automatically, without anyone copying the data by hand.
What an API is
An API describes which operations are available, how to send a request correctly, and what the response will contain. It also explains how to prove access and what happens when something goes wrong. You do not need to know how the other system works internally; it is enough to work with the data it is prepared to provide.
For example, a CRM may allow a client to:
- retrieve a customer record;
- create a deal;
- change a status;
- add a comment;
- request a list of tasks.
To help people and programs understand what an API can do, it is described in documentation—sometimes using a shared standard such as OpenAPI.
How the exchange works
Consider an example: a customer has placed an order on a website.
- Event. The order is created; this is the signal to begin the exchange.
- Request. The shop prepares a request to the CRM: “create a deal.”
- Access rights. The shop proves that it is allowed to do this.
- Transfer. The order data is sent to the CRM.
- Validation and execution. The CRM checks the format and creates the deal.
- Response. The CRM returns a result—“created”—or an error.
- Next step. The shop records the response and may, for example, create a task for a sales manager.
There are two ways to receive data: keep asking (“anything new yet?”) or receive a notification as soon as an event occurs. The second method is called a webhook.
Why “the data is transferred” is not enough
Transferring the data is only half the job. A reliable solution also answers uncomfortable questions: what happens if a service is unavailable, whether a request can be retried without creating a duplicate, where to find a failed operation, who may read and change fields, how different formats and reference data are reconciled, and what to do after the API version changes.
Without those answers, a demonstration may work while discrepancies accumulate in day-to-day operations. Reliability means making the whole process run like clockwork.
API, webhook, and RPA
An API is the official way to request data or an action. One system contacts another according to rules established by that system.
A webhook is a notification. One system tells another that something has happened: a payment went through or a status changed. After receiving the notification, the second system can request details through the API.
RPA is software working with an interface like a person: clicking buttons, filling in fields, and copying data. It is useful when no API exists. But it has a weak point: change the screen and the automation may break. That is why it needs additional supervision.
Security
Integrations use credentials and often gain access to sensitive information. Putting a lock on the door is not enough. You also need to decide who gets the keys, what belongs in the safe, who is allowed in, and how to record who entered.
That means using minimum permissions, storing keys securely, validating incoming data, limiting request frequency, keeping an action log, reviewing access regularly, and handling responses from external APIs safely.
An encrypted connection alone does not settle authorization or business rules. You still need explicit rules for who may enter and what they may do inside.
In brief
An API integration connects systems at the level of data and actions. Its quality is defined by more than a successful request: it also depends on behavior during failures, retries, change, and incorrect access. A good integration makes every exchange visible, verifiable, and recoverable.