Single and Double Quotes in String

Single quotes will ignore (not interpolate) any variables contained within.
EX: 'Not interpolated $variable'
Double quotes will interpolate any variables contained within.
EX: "Not interpolated $variable"

Basic Debugging Techniques

Run PHP through a website
Turn display_errors on
Check HTML source code

Description of $_SERVER

The $_SERVER variable contains server and execution environment information.
It is an array that contains information such as headers, paths, script locations, and data created by the web server.
The data in the array can be acessed by passing the name of a parameter into $_SERVER.

PHP Stuff

DOB: 12/17/2007

name length: 13

name: Vlad Kuletski

lowercase name: vlad kuletski

uppercase name: VLAD KULETSKI

fraction rounded to 4 decimal places: 1.2857

number formatted with commas: 3,005

concatenated: Vlad Kuletski, age: 17, DOB:12/17/2007!

Plain text: <h1>This is a header</h1>