CORE ARCHITECTURE

Term Definition
Client User-facing application that sends requests
Server System that processes requests and returns responses
Backend Server-side logic layer
Frontend User interface layer
API Interface to communicate between systems
REST API HTTP-based stateless API architecture
Stateless Server stores no session information
Stateful Server maintains session state
MVC Design pattern separating model, view, controller
Layered Architecture Separation into UI, logic, and data layers

NETWORKING & WEB

Term Definition
HTTP Protocol for client-server communication
HTTPS Encrypted HTTP communication
TCP Reliable connection-oriented protocol
UDP Fast connectionless protocol
DNS Resolves domain names to IP addresses
CDN Delivers static content from nearest server
Latency Time taken to respond to a request
Throughput Number of requests handled per second
Bandwidth Maximum data transfer capacity

DATABASE & STORAGE

Term Definition
Database Persistent data storage system
SQL Structured relational database
NoSQL Non-relational scalable database
Schema Structure of stored data
Index Data structure for fast lookup
Primary Key Unique identifier for records
Foreign Key Reference to another table’s primary key
Normalization Reducing data redundancy
Denormalization Adding redundancy for performance
ACID Database transaction guarantees
Read-heavy System with more reads than writes
Write-heavy System with more writes than reads

CACHING

Term Definition
Cache Temporary fast data storage
Redis In-memory key-value cache
Cache Hit Requested data found in cache
Cache Miss Requested data not in cache
TTL Time after which cache expires
Cache Invalidation Removing outdated cached data
Write-through Cache Writes update cache and DB together
Write-back Cache Writes update cache first, DB later

SCALABILITY & PERFORMANCE

Term Definition
Scalability Ability to handle increased load
Horizontal Scaling Adding more machines
Vertical Scaling Increasing machine capacity
Load Balancer Distributes traffic across servers
Auto-scaling Automatically adjust server count
Bottleneck Component limiting performance
SPOF Single component causing system failure

DISTRIBUTED SYSTEMS

Term Definition
Distributed System System running on multiple machines
Monolith Single deployable application
Microservices Independent services per feature
Service Discovery Mechanism to locate services
Inter-service Communication Data exchange between services

CAP THEOREM