Terms starting with "O"
OAuth 2.0
An authorisation framework that lets users grant third-party applications limited access to their resources without sharing passwords — using short-lived access tokens issued via defined flows for different client types.
CWE-287 OWASP A7:2021
4w ago
security intermediate
Open Graph Protocol
Meta tags that control how a page appears when shared on social platforms — title, description, image, and URL shown in link previews on Facebook, LinkedIn, Slack, Discord, and Twitter/X.
1mo ago
frontend beginner
Optimistic Locking
A concurrency pattern using a version column to detect conflicting concurrent writes — no row locks held between read and write.
1mo ago
database advanced
OAuth 2.0 PKCE — Proof Key for Code Exchange PHP 7.0+ An OAuth 2.0 extension that prevents authorisation code interception attacks in public clients (SPAs, mobile apps) by binding each authorisation request to a cryptographic secret the client generates.
1mo ago
cryptography intermediate
Object.freeze / Object.seal ES5
Object.freeze() prevents all property changes (add/modify/delete), Object.seal() prevents add/delete but allows modification — both are shallow, not deep.
2mo ago
javascript intermediate
Offline-First Design
An architectural approach where applications are designed to work fully without a network connection by default, treating connectivity as an enhancement rather than a requirement.
2mo ago
mobile advanced
OLAP vs OLTP
OLTP (Online Transaction Processing) optimises for many small, fast read/write operations — your main application database. OLAP (Online Analytical Processing) optimises for few, large analytical queries scanning millions of rows — your reporting and analytics database.
2mo ago
database intermediate
On-Call & Runbooks
A runbook documents how to diagnose and resolve specific alerts — on-call engineers shouldn't have to think from scratch at 3am; the runbook provides the playbook.
2mo ago
observability beginner
Opaque Objects & GdImage/CURLHandle PHP 8.0+
PHP 8.0 replaced resource types (gd, curl, xml) with opaque objects — GdImage, CurlHandle, XMLParser — improving type safety and OOP integration.
2mo ago
php intermediate
OPcache Internals — How Bytecode Caching Works PHP 5.5+
OPcache compiles PHP source files to bytecode once and stores the result in shared memory — subsequent requests skip parsing and compilation entirely, making PHP 5–10x faster for I/O-bound workloads.
2mo ago
php intermediate
OPcache Preloading (PHP 7.4) PHP 7.4+
OPcache preloading (PHP 7.4) compiles PHP files into shared memory at server start — eliminating per-request compilation of framework core files for significant performance gains.
2mo ago
php advanced
OpenTelemetry
OpenTelemetry (OTel) is the open standard for telemetry — a vendor-neutral SDK for traces, metrics, and logs that exports to any backend (Jaeger, Datadog, Honeycomb, Prometheus).
2mo ago
observability intermediate
Optimistic Locking
Optimistic locking detects conflicts at commit time using a version number — no locks held during the transaction, high throughput for low-contention scenarios.
2mo ago
concurrency intermediate
ORM — Object-Relational Mapper PHP 7.0+
A library that maps database rows to PHP objects and vice versa — handling SQL generation, relationships, and lazy loading, at the cost of hiding query behaviour that can cause N+1 problems if used carelessly.
2mo ago
database beginner
OWASP API Security Top 10
The OWASP API Security Top 10 lists the most critical API vulnerabilities — a separate list from the web application Top 10, covering risks specific to REST, GraphQL, and other API surfaces such as broken object-level authorisation and unrestricted resource consumption.
2mo ago
security intermediate
Object Cloning & Security Implications PHP 5.0+
clone creates a shallow copy — nested objects are still shared references. Implement __clone() for deep copy and audit what sensitive state gets duplicated.
2mo ago
security intermediate
Out of Memory Errors (memory_limit) PHP 5.0+
PHP enforces memory_limit in php.ini — exceeding it triggers a fatal E_ERROR that cannot be caught with set_error_handler().
2mo ago
php intermediate
Offline-First Design ES2015
Designing applications to work without a network connection by default — storing data locally, syncing when online, and handling conflicts gracefully.
2mo ago
mobile advanced
On-Call Culture & Runbooks
Sustainable on-call practices — fair rotation, blameless postmortems, actionable alerts, and well-maintained runbooks that reduce mean time to recovery and prevent burnout.
2mo ago
devops intermediate
OPcache Tuning PHP 5.5+ OPcache stores compiled PHP bytecode in shared memory, eliminating recompilation on every request — proper tuning is the single highest-impact PHP performance configuration.
2mo ago
php intermediate