Here are some of the ways the latest version differs from the old:

• Arachnophilia 5.5 greatly improves the text editing / syntax coloring scheme and the number of supported file types. It also introduces two new beautification (code formatting) engines, for Ruby programs and and Bash shell scripts.
• Arachnophilia 5.4 introduces support for international characters and content, a feature described more fully here.
• Arachnophilia 5.3 has a new feature called "HTML Validate" that will help you find and correct structural errors in your pages. In essence, this feature takes your page apart, tells you what it finds, and allows you to navigate your page in a hierarchical sense, identifying areas for improvement.
• Arachnophilia 5.3 has a feature called "Instant Search." Here's how it works: when you begin typing the word you want to find, Arachnophilia begins searching immediately, as you type, using the letters you have typed so far.
• Arachnophilia 5.3 has a very advanced macro editor that allows you to create, delete, and edit commands, including nearly all the commands one thinks of as "hard-wired" into a program. For example, the main application menu bar and toolbar are part of the Arachnophilia macro system. You can even right-click toolbar buttons and edit them!
• Arachnophilia can dynamically link to external, user-provided Java classes, and those classes can process your documents. This lets you customize Arachnophilia to a remarkable degree.
• When you exit Arachnophilia, it remembers everything — all your changes to menus and toolbars, what documents you were working with, any words you added to the spell checker, even your most recent search and replace strings.
• Each person who logs onto your system or network and accesses Arachnophilia 5.3 gets a fresh installation of the default user files. The files are plain-text, human readable files, and changes can be made both inside and outside Arachnophilia.

Arachnophilia is the latest addition to a series of programs that stretches over decades — going back to "Apple Writer," which ran on the original Apple II computer, a computer with a 1 MHz clock and at most 16 KB of RAM (originally). "Apple Writer" also had an automation and user-customization ability, at a time when that was very uncommon.

Most modern programs require you to learn from them, but the basic design goal of Arachnophilia is to learn as much as it can from you. Arachnophilia lets you instruct it, tell it which keys do what, and include new instructions that meet your requirements.

If you begin working with Arachnophilia, soon you will create a new toolbar button, give it some instructions (including Arachnophilia system commands), a name, an icon, and a comment that floats above the button when the mouse is over it (called a "tooltip") — and when you do, you will begin to understand how Arachnophilia differs from other programs.