Terms starting with "P"
P50/P95/P99 Latency Percentiles
Latency percentiles (P50, P95, P99) tell you what most users experience — P99 means '99% of requests are faster than this', revealing the worst experiences that averages hide.
6mo ago
Observability beginner
Page Visibility API
HTML5
The Page Visibility API tells you when a tab is hidden or visible — use it to pause animations, polls, and video when the user switches tabs.
6mo ago
JavaScript beginner
password_hash() — Native Bcrypt (PHP 5.5)
PHP 5.5+
PHP 5.5 added password_hash() and password_verify() — the only correct way to hash and verify passwords. Never use MD5, SHA1, or unsalted hashes.
6mo ago
PHP beginner
PCNTL Signals in CLI PHP
PHP 7.1+
6
The PCNTL extension lets CLI PHP scripts handle OS signals (SIGTERM, SIGINT, SIGUSR1) — enabling graceful shutdown and hot reload in long-running daemons.
6mo ago
PHP advanced
Permissions API
HTML5
The Permissions API (navigator.permissions.query()) lets you check the current state of browser permissions — granted, denied, or prompt — before requesting sensitive APIs.
6mo ago
JavaScript intermediate
Pessimistic Locking
5
Pessimistic locking acquires an exclusive lock immediately on read — preventing any concurrent modification. Right for high-contention scenarios but reduces throughput.
6mo ago
Concurrency intermediate
PHP 3 — Birth of the Language (Rasmus Lerdorf)
PHP 3.0+
1
PHP 3 (1997) was the first version called 'PHP' — a complete rewrite by Zeev Suraski and Andi Gutmans that transformed Rasmus Lerdorf's Personal Home Page tools into a proper language.
6mo ago
PHP beginner
PHP 4 Objects Passed by Value (Pre-5 Gotcha)
PHP 4.0+
1
PHP 4 copied objects on assignment — $b = $a created a full clone. PHP 5+ passes object handles by value (reference semantics). This was the biggest PHP 4 pain point.
6mo ago
PHP intermediate
PHP 4 — Zend Engine 1, Classes Without OOP
PHP 4.0+
4
PHP 4 (2000) introduced the Zend Engine 1.0 — dramatically improving performance and adding basic classes, though objects were passed by value and OOP was rudimentary.
6mo ago
PHP beginner
PHP 6 — The Version That Never Shipped
PHP 6 was a major development effort (2005–2010) that aimed to bring native Unicode support to PHP but was abandoned due to complexity and performance problems — its features were later cherry-picked into PHP 5.3 and 5.4.
6mo ago
PHP beginner
PHP 8 — Key Features
PHP 8.0+
PHP 8.0–8.4 introduced match expressions, named arguments, union types, nullsafe operator, fibers, enums, readonly properties, first-class callables, and a JIT compiler — the most significant evolution of the language since PHP 5.
6mo ago
PHP intermediate
PHP 8.5 — What's Coming
PHP 8.5+
PHP 8.5 is in active development (expected late 2025). Confirmed additions include pipe operator |>, first-class callable improvements, and several standard library additions. The release follows PHP's annual November release cycle.
6mo ago
PHP beginner
PHP CSV Handling (fgetcsv / str_getcsv)
PHP 5.3+
PHP provides fgetcsv() for reading CSV line-by-line from a file handle and str_getcsv() for parsing a CSV string — both handle quoted fields, embedded commas, and escaped characters correctly where explode() does not.
6mo ago
PHP beginner
PHP Execution Model — Shared-Nothing Architecture
PHP 5.0+
3
Each PHP request runs in a completely isolated process or thread — no memory, globals, or state is shared between requests. Every request bootstraps the entire application from scratch and discards everything when it ends.
6mo ago
PHP intermediate
PHP Garbage Collection Internals (Cycle Collector)
PHP 5.3+
1
PHP uses reference counting as its primary memory management strategy — when a value's reference count drops to zero it is freed immediately. A secondary cycle collector handles circular references that reference counting alone cannot free.
6mo ago
PHP advanced
PHP Mail & SMTP
PHP 4.0+
Sending email from PHP using mail(), SMTP libraries like PHPMailer or Symfony Mailer, or transactional email APIs — with critical configuration for deliverability, security, and reliability.
6mo ago
PHP beginner
PHP Memory Model — Zval & Copy-on-Write
PHP 7.0+
2
PHP stores every value in a zval (Zend value) container that holds the type, value, and a reference count. Arrays and strings are copied lazily — the copy only happens when one copy is modified (copy-on-write), making passing large values cheap until mutation.
6mo ago
PHP advanced
PHP SAPI Types (FPM, CLI, Embed)
PHP 4.0+
SAPI (Server API) defines how PHP is invoked — php-fpm for web requests, php-cli for commands, embed for C extensions — each has different lifecycle and configuration.
6mo ago
PHP intermediate
PHP Sessions
PHP 4.0+
1
Server-side state storage identified by a cookie-based session ID — PHP's built-in mechanism for persisting data across HTTP requests, with security implications for how the session is started, stored, and terminated.
6mo ago
PHP beginner
PHP Sodium Extension (Libsodium)
PHP 7.2+
5
The Sodium extension (bundled since PHP 7.2) provides modern, misuse-resistant cryptography via the libsodium C library — covering authenticated encryption, key exchange, password hashing with Argon2, and digital signatures with a simple, safe API.
6mo ago
PHP advanced