Application Programming Interface, is a set of rules and protocols that enables different software applications to communicate with one another. It acts as an intermediary, allowing applications to exchange data, features, and functionalities without needing to understand the underlying code or architecture of each other.
HTTP Verbs
Also known as HTTP methods, are fundamental components of the Hypertext Transfer Protocol (HTTP) used to specify the desired action to be performed on a resource.
GET: Retrieve data from a specified resource.POST: Submit data to create a new resource or trigger an action.PUT: Update or replace an existing resource at a specified URL.PATCH: Apply partial modifications to an existing resource.DELETE: Remove a specified resource.HEAD: Retrieve only the headers of a resource without the body.OPTIONS: Describe the communication options for the target resource, including supported methods.CONNECT: Establish a tunnel to the server identified by the target resource (often for secure connections).TRACE: Perform a diagnostic loop-back test along the path to the target resource.
HTTP Status Codes
HTTP status codes are three-digit responses from a server indicating the outcome of a client’s request. They are crucial for understanding how web communication functions and diagnosing issues. These codes are categorized into five main classes, each represented by the first digit of the code.
1xx: Informational
These codes indicate that the server has received the request and is continuing to process it.
- 100 Continue: The initial part of the request has been received.
- 101 Switching Protocols: The server is changing protocols as requested by the client.
2xx: Success
This category signifies that the request was successfully received, understood, and accepted.
- 200 OK: The request was successful, and the server returned the requested data.
- 201 Created: A new resource has been created as a result of the request.
- 204 No Content: The request was successful, but there is no content to return.
3xx: Redirection
These codes indicate that further action is needed to complete the request.
- 301 Moved Permanently: The requested resource has been permanently moved to a new URL.
- 302 Found: The resource is temporarily located at a different URL.
- 304 Not Modified: Indicates that the resource has not changed since the last request.
4xx: Client Error
This category indicates that there was an error with the client’s request.
- 400 Bad Request: The server could not understand the request due to malformed syntax.
- 401 Unauthorized: The client must authenticate itself to get the requested response.
- 404 Not Found: The server cannot find the requested resource.
5xx: Server Error
These codes indicate that the server failed to fulfill a valid request.
- 500 Internal Server Error: A generic error indicating an unexpected condition on the server.
- 503 Service Unavailable: The server is currently unable to handle requests due to temporary overload or maintenance.
Query Strings
A query string is a part of a URL that sends additional information to a web server. It begins with a question mark ? and consists of key-value pairs separated by ampersands &.
Example URL: https://myapi.com/page?key1=:value&key2=:value
HTTP Headers
HTTP headers are also a key-value pairs sent with HTTP requests and responses that provide essential metadata about the communication. They help define aspects such as content type, caching behavior, and authentication details.