What Is an API? Meaning in Simple Words

Description

Glossary What is an API?

An API (application programming interface) is a defined set of rules through which one piece of software asks another for data, or asks it to do something, without a person using a screen. It works as a contract: send a request in the agreed form, and you get a response in the agreed form.

Talk to a technology expert Last updated 2 October 2026

A plain example

Your website sells a course for ₹1,499. It does not handle card or UPI details itself; a payment gateway does. The two talk through the gateway's API.

Your server sends a request: "create a payment of ₹1,499 for order 1042".

The gateway replies with a reference for that payment.

The customer pays on the gateway's screen.

Your server asks, or is told by a webhook , whether the payment succeeded.

A request and its response are small blocks of structured text. An illustration of the shape, not any provider's exact format:

{ "amount": 149900, "currency": "INR", "receipt": "order_1042" }

{ "id": "pay_ref_8841", "status": "created", "amount": 149900 }

Nobody at the gateway does anything by hand, and your developer never sees the gateway's internal code. The API is the whole of the relationship, which is why MDN describes it as a contract between the application offering it and the software using it.

Why it matters when you commission software

"API integration" in a quote can mean an afternoon or a month. These questions find out which:

Question to ask

Why

Does the other system have a documented API?

If it does not, the connection needs file exports or manual work, and costs more.

What does the API not allow?

Many expose only part of what the screens can do.

Are there usage limits or per-call charges?

They shape the design and the running cost.

Whose account holds the API keys?

They should be your company's, not the developer's.

What happens when the provider changes its API?

Providers retire old versions. Someone must be responsible for updates.

WavX builds both sides: connections to other systems, listed under integrations , and APIs for your own software under API development .

Related terms

Webhook : the reverse direction. The other system tells yours when something happens.

Endpoint: one address in an API that does one job, such as "create a payment".

API key or token: the credential that proves a request comes from you.

REST and GraphQL: two common styles of web API, compared in REST vs GraphQL .

Frequently asked questions

What does API stand for?

Application programming interface. 'Interface' is the important word: it is the point where two pieces of software meet, in the same way a screen is the point where software meets a person.

Is an API the same as an integration?

No. The API is what the other system offers. The integration is the work of connecting your system to it: sending the right requests, handling errors and keeping the two sets of data in agreement.

Does my own software need an API?

It does if anything other than its own screens must talk to it: a mobile app, a partner's system, an accounting package. If the software will only ever be used through its own web pages, a public API can wait.

Sources

MDN Web Docs glossary: API · read 2 October 2026

Related

API development

Integrations

What is a webhook?

REST vs GraphQL: which API should you use?

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