Whitespace and Case-Sensitivity

Like all PHP programs, the examples in this section consist of a series of statements, each of which end with a semicolon. You can put multiple PHP statements on the same line of a program as long as they are separated with a semicolon. You can put as many blank lines between statements as you want. The PHP interpreter ignores them. The semicolon tells the interpreter that one statement is over and another is about to begin. No whitespace at all or lots and lots of whitespace between statements doesn't affect the program's execution. (Whitespace is programmer-speak for blank-looking characters such as space, tab, and newline.)
In practice, it's good style to put one statement on a line and to put blank lines between statements only when it improves the readability of your source code. The spacing in Examples Example 1-9 and Example 1-10 is bad. Instead, format your code as in Example 1-11.

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Basic Rules of PHP Programs

This section lays out some ground rules about the structure of PHP programs. More foundational than the basics such as "how do I print something" or "how do I add two numbers", these proto-basics are the equivalent of someone telling you that you should read pages in this book from top to bottom and left to right, or that what's important on the page are the black squiggles, not the large white areas.
If you've had a little experience with PHP already or you're the kind of person that prefers playing with all the buttons on your new DVD player before going back and reading in the manual about how the buttons actually work, feel free to skip ahead to Chapter 2 now and flip back here later. If you forge ahead to write some PHP programs of your own, and they're behaving unexpectedly or the PHP interpreter complains of "parse errors" when it tries to run your program, revisit this section for a refresher.
Start and End TagsEach of the examples you've already seen in this chapter uses as the PHP end tag. The PHP interpreter ignores anything outside of those tags. Text before the start tag or after the end tag is printed with no interference from the PHP interpreter.

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