There is no single right answer to every problem and PHP is no exception. The dynamic programming language has its strengths and its weaknesses like any other language. PHP integrates very well with HTML and has hundreds of functions that make it a very capable programming language for a variety of tasks. It also has the ability to interact with the operating system like a scripting language. PHP is also widely held as the way to interact with databases of almost every type.

PHP is the go to guy for Web programming languages but are there things better left to Perl, Ruby, Java, JavaScript or Python? You bet there are. In particular, PHP is not thread safe—which means that multiple instances of the same routine may interact with each other, resulting in a crash on the Web server. PHP has suffered its share of security problems, and it isn't particularly well-suited to large or extremely complex site implementations.

Despite some of its significant shortcomings, PHP is perhaps the most popular Web scripting language currently used in the world. Why is that? Some of the reasons may surprise you.

Editor's Note: As the number of comments on this article demonstrate, several readers disagreed with our author's opinions. Those readers may wish to also read our followup article: PHP's Enterprise Strengths and Weaknesses, Take 2, in which Zend's John Coggeshall responds with his own list of the Good, the Bad and the Ugly of PHP application development.

PHP's Shining Beacon

Several dynamic or "scripting" languages, including PHP, Perl, Java and others, have their roots in the C language, which makes them a natural fit for developers making the transition from traditional application programming to Web programming. This makes the learning curve far less steep for those used to standard procedural languages. PHP has the advantage since it also integrates very well with HTML.

In fact, its full name is PHP: Hypertext Preprocessor (one of those famous Unix recursive acronyms), which means that it understands hypertext (HTML) without any special API or modifications. An API, application programming interface, is a set of libraries that allow programmers to interact with operating systems, databases or other applications by referencing those libraries inside an application. PHP has a long list of APIs and functions that expand its capability beyond that of any other contemporary Web scripting language.

PHP has enjoyed a long-lived association with databases, especially MySQL. However, PHP plays equally well with Oracle, DB2, SQLite, PostgreSQL, Sybase and Microsoft's SQL Server. Migrating from one database server to another is usually quite simple since most of PHP's functions have a common naming convention. A programmer can do simple global pattern replacements to change from one database brand to another. The following is an example of some often used MySQL functions and their Microsoft SQL Server equivalents.

As you can see in the table, an application that accesses a MySQL database can be redesigned as a Microsoft SQL Server application with minimal effort.

PHP is available for almost every current operating system. This makes the code portable to other platforms with few, if any, changes. If you run a PHP website on Windows with IIS and it crashes, you can use the PHP scripts and pages on a PHP-enabled Linux server with minor modifications. You have to change any absolute paths and some parameters only in the PHP configuration file. For similar systems (Unix to Linux), you may only have to copy the files to the new server and restart your Web server.

PHP enjoys such widespread popularity because:

• It is easy to learn: Its C-like syntax makes it an easy language to learn for programmers and nonprogrammers alike.
• It blends well with HTML: You can mix PHP scripts right inside your HTML or place HTML tags and code inside PHP files.
• PHP has a vast library of functions and APIs: PHP's ability to interact with LDAP, databases and the file system makes it a great "one stop shop" for developers.
• You can rapidly create Web applications and database-backed applications: PHP is so often used with databases, especially open-source databases, that several books are available on the shared topic of PHP and MySQL.
• It is cross-platform capable: PHP is used on Windows, Linux, commercial flavors of Unix and MacOS X.

When should you use PHP?

• Creating an intranet site.
• Prototyping an application that will be converted to Java or some other language.
• Creating a Web database application.
• Deploying an inexpensive or quick solution.
• Using ready-made apps from Sourceforge.net or other sites.