Tech Interview Glossary

Every technical term you need to know, explained clearly.

A

API

An Application Programming Interface is a set of protocols and tools that allows different software applications to communicate with each other. In interviews, you may be asked to design REST APIs, explain API versioning, or discuss rate limiting strategies.

Agile

A project management and software development methodology that emphasizes iterative delivery, cross-functional collaboration, and rapid response to change. Agile frameworks include Scrum, Kanban, and SAFe. Behavioral interviews often explore your experience with agile ceremonies, retrospectives, and handling changing requirements.

B

Big O Notation

A mathematical notation used to describe the upper bound of an algorithm's time or space complexity as input size grows. Common complexities include O(1), O(log n), O(n), O(n log n), and O(n^2). Nearly every coding interview expects you to analyze and optimize the Big O complexity of your solution.

C

CI/CD

Continuous Integration and Continuous Delivery (or Deployment) is a set of practices that automate building, testing, and deploying code changes. CI ensures every commit is validated by automated tests, while CD automates the release pipeline. Interviewers often ask about pipeline design, rollback strategies, and deployment best practices.

Cache

A high-speed data storage layer that stores a subset of data so future requests can be served faster than accessing the primary data source. Caching strategies include write-through, write-back, and write-around. Interview questions often cover cache invalidation, eviction policies (LRU, LFU), and cache stampede prevention.

Code Review

The systematic examination of source code by peers to find bugs, improve quality, and share knowledge. Effective code reviews focus on correctness, readability, performance, and adherence to coding standards. Interview questions may cover your code review process, how you give constructive feedback, and how you handle disagreements.

D

Docker

A platform for building, shipping, and running applications inside lightweight, portable containers. Containers package code with all dependencies, ensuring consistent environments from development to production. Interview topics include Dockerfile best practices, image layering, and container orchestration.

Database Index

A data structure that improves the speed of data retrieval operations on a database table at the cost of additional storage and slower writes. Common types include B-tree, hash, and composite indexes. Interviewers ask about when to create indexes, covering indexes, and how to diagnose slow queries.

Design Patterns

Reusable solutions to commonly occurring problems in software design. Categories include creational (Singleton, Factory), structural (Adapter, Decorator), and behavioral (Observer, Strategy). Interview questions may ask you to apply a pattern to a scenario or explain trade-offs between patterns.

G

GraphQL

A query language for APIs developed by Facebook that lets clients request exactly the data they need. Unlike REST, GraphQL uses a single endpoint and a strongly typed schema. Interviewers may ask you to compare it with REST or design a schema for a given domain.

I

Integration Testing

Testing that verifies multiple components or services work together correctly. Unlike unit tests, integration tests exercise real dependencies such as databases, APIs, or message queues. Interview topics include test environment management, contract testing, and the testing pyramid.

K

Kubernetes

An open-source container orchestration platform that automates deploying, scaling, and managing containerized applications. Key concepts include pods, services, deployments, and ingress controllers. Interviewers may ask about scaling strategies, rolling updates, and service discovery.

L

Load Balancer

A device or software that distributes incoming network traffic across multiple servers to ensure no single server is overwhelmed. Common algorithms include round-robin, least connections, and consistent hashing. System design interviews frequently ask about load balancing at different layers (L4 vs L7) and health checks.

M

Microservices

An architectural pattern where an application is structured as a collection of loosely coupled, independently deployable services. Each service owns its data and communicates over lightweight protocols. Expect interview questions about service boundaries, data consistency, and inter-service communication.

R

REST

Representational State Transfer is an architectural style for designing networked applications. RESTful APIs use HTTP methods (GET, POST, PUT, DELETE) to perform CRUD operations on resources. Interview questions often cover REST constraints, statelessness, and resource naming conventions.

S

SOLID Principles

Five object-oriented design principles: Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion. These principles guide developers in creating maintainable and extensible software. Interviewers may ask you to identify SOLID violations in code or refactor a class hierarchy using these principles.

Sprint

A fixed-length iteration, typically one to four weeks, during which a development team works to complete a set of planned work items. Sprints include planning, daily standups, review, and retrospective ceremonies. Interviewers may ask about how you estimate story points, handle scope creep, or prioritize a sprint backlog.

T

Technical Debt

The implied cost of future rework caused by choosing an expedient solution now instead of a better approach that would take longer. Types include deliberate (shortcuts for deadlines) and inadvertent (poor design from lack of knowledge). Interviewers ask how you identify, quantify, and prioritize paying down technical debt.

U

Unit Testing

The practice of testing individual units of code (functions, methods, classes) in isolation to verify they produce expected results. Frameworks include Jest, JUnit, and pytest. Interviewers often ask you to write unit tests for your solution, discuss test coverage strategies, or explain mocking and stubbing.

V

Version Control

A system that records changes to files over time so you can recall specific versions later. Git is the most widely used version control system. Interview questions cover branching strategies (Git Flow, trunk-based development), merge conflict resolution, rebasing, and collaboration workflows.