PHP

AJAX Example (w3Schools) Apache Server Setup
AppleScript ofr Terminal Automation
Array Functions (w3Schools)
Arrays
Arrays Sorting
Atom Documentation

Basics

Classes & Objects
Client URL Library (curl)
Coding Standards

Date
Date Formats
Date/Time Functions Debugging Basics
Debugging with xDebug

Error Checking
Error Functions Exception Object
File Permissions
Files and Folders
Files: How to Lock
Formatting Strings
File System Functions (w3Schools) Functions

getdate() Key|Value Pairs
GLOBALS

JSON

Microtime

Objects

PayPal
PEAR (PHP Extension and Application Repository)
PEAR Installation
PECL (PHP Extension Community Library)
Permissions
PHP7 Improvements PHP Examples (w3Schools) PHP Live Regex
PHP Manual
PHP Playground
PHP Reference (w3schools.com)
PHP Sandbox
POST Basics

Reflection
Regular Expressions
Reserved Words

Sending an E-Mail in Text Format
Sending an E-Mail in HTML Format
Sending an SMS
Strings
String Functions (w3Schools)
Terminal Cheat Sheet
If/then Ternary Logic
The 10 Most Common Mistakes
Time
Time Formats
Tutorial at w3shools.com
Tutorial (tutorialspoint)

W3C Markup Validation Service
Web Fundamentals