Aptana Studio is based on the Eclipse platform and you can either install Aptana Studio as a standalone application or, if you already have Eclipse installed, you can add Studio as a plugin to your Eclipse installation.
If your work is primarily web application development, we recommend installing the standalone Aptana Studio; if your work also involves Java development, we recommend installing Studio as an Eclipse plugin.
Is your computer Aptana Studio ready? Aptana Studio System Requirements
Have an older version of Studio installed? Updating your version of Aptana Studio