API Glossary - Technical Terms & Definitions
Welcome to the API Codex Technical Glossary. This comprehensive reference defines key terms and concepts used throughout our documentation to help you better understand API development and integration.
A
API (Application Programming Interface)
A set of protocols, tools, and definitions that allow different software applications to communicate with each other. APIs define the methods and data formats that applications can use to request and exchange information.
API Key
A unique identifier used to authenticate requests to an API. API keys help track and control how the API is being used and prevent unauthorized access.
API Gateway
A server that acts as an intermediary between clients and backend services, handling tasks like request routing, composition, authentication, and rate limiting.
API Endpoint
A specific URL where an API can be accessed by a client application. Each endpoint corresponds to a specific function or resource.
Asynchronous Processing
A method of processing requests where the client doesn't wait for the operation to complete. The API returns immediately with a job ID, and results are delivered later via webhook or polling.
Authentication
The process of verifying the identity of a user or application attempting to access an API. Common methods include API keys, OAuth, and JWT tokens.
Authorization
The process of determining what actions an authenticated user or application is allowed to perform. This is different from authentication, which only verifies identity.
B
Base URL
The root URL for all API endpoints. For example, https://api.example.com/v1 where all endpoint paths are appended.
Batch Processing
The ability to process multiple requests or operations in a single API call, improving efficiency and reducing the number of HTTP requests.
Bearer Token
A type of access token used in HTTP authentication. It's sent in the Authorization header as Bearer <token>.
C
Cache
A temporary storage mechanism that stores copies of API responses to reduce latency and server load for frequently requested data.
CORS (Cross-Origin Resource Sharing)
A security mechanism that allows or restricts resources on a web page to be requested from another domain outside the domain from which the resource originated.
cURL
A command-line tool for transferring data using various network protocols, commonly used for testing APIs.
D
DNS (Domain Name System)
A hierarchical system that translates human-readable domain names (like example.com) into IP addresses that computers use to identify each other on the network.
DKIM (DomainKeys Identified Mail)
An email authentication method that allows the receiver to check that an email was actually sent and authorized by the owner of that domain.
DMARC (Domain-based Message Authentication, Reporting & Conformance)
An email authentication protocol that uses SPF and DKIM to determine the authenticity of an email message.
DNS Propagation
The process of updating DNS records across the internet, which can take time as DNS servers worldwide update their cached information.
E
Endpoint
See API Endpoint.
Error Code
A standardized code returned by an API to indicate the type of error that occurred. Common HTTP error codes include 404 (Not Found), 401 (Unauthorized), and 500 (Internal Server Error).
ETL (Extract, Transform, Load)
A data integration process that extracts data from sources, transforms it into a usable format, and loads it into a destination system.
F
Fallback
An alternative course of action when the primary method fails. In APIs, this might mean using a secondary endpoint or cached data when the primary service is unavailable.
G
GET Request
An HTTP method used to retrieve data from a server. GET requests should not modify server data.
GDPR (General Data Protection Regulation)
A European Union regulation on data protection and privacy that affects how APIs must handle personal data.
GraphQL
A query language for APIs that allows clients to request exactly the data they need, providing more flexibility than traditional REST APIs.
H
Header
Metadata sent with an HTTP request or response. Common headers include Content-Type, Authorization, and User-Agent.
HIPAA (Health Insurance Portability and Accountability Act)
US legislation that provides data privacy and security provisions for safeguarding medical information.
HTTP (Hypertext Transfer Protocol)
The foundation of data communication on the web, defining how messages are formatted and transmitted.
HTTPS (HTTP Secure)
An extension of HTTP that uses encryption (TLS/SSL) to secure communication between clients and servers.
I
Idempotent
An operation that produces the same result regardless of how many times it's executed. PUT and DELETE requests should be idempotent.
IP Address
A numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.
IP Whitelisting
A security feature that allows access only from specified IP addresses, blocking all others.
J
JSON (JavaScript Object Notation)
A lightweight data-interchange format that's easy for humans to read and write and easy for machines to parse and generate. The most common format for API responses.
JWT (JSON Web Token)
A compact, URL-safe token format used for securely transmitting information between parties, commonly used for authentication.
L
Latency
The time delay between a request being sent and a response being received. Lower latency means faster API performance.
Load Balancing
The process of distributing network traffic across multiple servers to ensure no single server becomes overwhelmed.
M
Microservices
An architectural style that structures an application as a collection of small, independent services that communicate via APIs.
MX Record (Mail Exchange Record)
A DNS record that specifies the mail server responsible for accepting email messages on behalf of a domain.
N
NLP (Natural Language Processing)
A branch of artificial intelligence that helps computers understand, interpret, and manipulate human language.
NULL
A value representing the absence of data or an undefined value.
O
OAuth
An open standard for access delegation, commonly used for token-based authentication and authorization.
OCR (Optical Character Recognition)
Technology that converts images of text into machine-encoded text, used in document parsing APIs.
OpenAPI
A specification for describing RESTful APIs in a machine-readable format, formerly known as Swagger.
P
Pagination
A technique for dividing large result sets into smaller, manageable pages. Common parameters include page, limit, and offset.
Parsing
The process of analyzing and converting data from one format into a structured format that can be easily processed.
Payload
The actual data being transmitted in an API request or response, excluding headers and metadata.
PII (Personally Identifiable Information)
Any data that could potentially identify a specific individual, such as name, email address, or social security number.
POST Request
An HTTP method used to send data to a server to create or update a resource.
PUT Request
An HTTP method used to update or replace a resource on the server.
PTR Record (Pointer Record)
A DNS record used for reverse DNS lookups, mapping an IP address to a domain name.
Q
Query Parameter
Data appended to a URL after a question mark (?), used to pass additional information to an API endpoint. Example: ?name=example&type=A.
Query String
The part of a URL that contains query parameters.
Quota
A limit on the amount of resources or number of requests that can be used within a specific time period.
R
RapidAPI
A marketplace and platform for discovering, testing, and connecting to thousands of APIs. API Codex APIs are hosted on RapidAPI.
Rate Limiting
A technique to control the number of requests a client can make to an API within a specified time period, preventing abuse and ensuring fair usage.
REST (Representational State Transfer)
An architectural style for designing networked applications, using HTTP methods and following specific principles like statelessness and resource-based URLs.
RESTful API
An API that follows REST architectural principles.
Response Time
The time it takes for an API to process a request and return a response.
Retry Logic
Code that automatically retries failed requests after a delay, typically with exponential backoff.
Reverse DNS Lookup
The process of determining the domain name associated with an IP address, the opposite of standard DNS resolution.
S
SDK (Software Development Kit)
A collection of tools, libraries, documentation, and code samples that make it easier to develop applications for a specific platform or API.
SERP (Search Engine Results Page)
The page displayed by a search engine in response to a user's query.
SPF (Sender Policy Framework)
An email authentication method that specifies which mail servers are authorized to send email on behalf of a domain.
SSL/TLS (Secure Sockets Layer / Transport Layer Security)
Cryptographic protocols designed to provide secure communication over a computer network.
Status Code
A three-digit number returned by a server indicating the result of an HTTP request (e.g., 200 for success, 404 for not found).
Synchronous Processing
A method where the client waits for the API to complete processing before receiving a response.
T
Throttling
See Rate Limiting.
Timeout
The maximum time a client will wait for a response from an API before considering the request failed.
TLS (Transport Layer Security)
See SSL/TLS.
Token
A piece of data used for authentication and authorization. Tokens can be API keys, JWTs, or OAuth tokens.
TTL (Time To Live)
A value in a DNS record that determines how long the record should be cached before being refreshed.
U
Uptime
The percentage of time that an API is operational and available. For example, 99.9% uptime means the service is down for approximately 43 minutes per month.
URI (Uniform Resource Identifier)
A string of characters that identifies a resource on the internet.
URL (Uniform Resource Locator)
A specific type of URI that provides the location and method for accessing a resource.
V
Validation
The process of checking whether data meets specific criteria or requirements before processing.
Version Control
A system for managing changes to code or API specifications over time. Also refers to API versioning (e.g., /v1/, /v2/).
W
Webhook
A method for receiving real-time notifications when specific events occur. Instead of polling for updates, the API sends HTTP POST requests to a specified URL when events happen.
WHOIS
A protocol for querying databases that store information about domain name registrations.
X
XML (eXtensible Markup Language)
A markup language that defines rules for encoding documents in a format that is both human-readable and machine-readable. Less common than JSON in modern APIs.
x-rapidapi-key
The HTTP header used to authenticate requests to APIs hosted on RapidAPI.
x-rapidapi-host
The HTTP header that specifies which API on RapidAPI you're calling.
Need More Help?
Can't find a term you're looking for? Here are additional resources:
- Getting Started Guide - Learn the basics of using API Codex
- API Documentation - Detailed reference for each API
- FAQ Page - Common questions and answers
- Best Practices - Production-ready implementation patterns
Found an error or want to suggest a new term? Contact our support team through RapidAPI.