Oracle Database

Oracle Database 10g Express EditionFree to develop, deploy, and distribute
Oracle Database 10g Express Edition (Oracle Database XE) is an entry-level, small-footprint database based on the Oracle Database 10g Release 2 code base that's free to develop, deploy, and distribute; fast to download; and simple to administer. Oracle Database XE is a great starter database for:
Developers working on PHP, Java, .NET, XML, and Open Source applications
DBAs who need a free, starter database for training and deployment
Independent Software Vendors (ISVs) and hardware vendors who want a starter database to distribute free of charge
Educational institutions and students who need a free database for their curriculum With Oracle Database XE, you can now develop and deploy applications with a powerful, proven, industry-leading infrastructure, and then upgrade when necessary without costly and complex migrations. Read what users say about Oracle Database XE.
Oracle Database XE can be installed on any size host machine with any number of CPUs (one database per machine), but XE will store up to 4GB of user data, use up to 1GB of memory, and use one CPU on the host machine.
Download Oracle Database 10g Express Edition
After installation, be sure to register for an exclusive Oracle Database 10g Express Edition Discussion Forum hosted by Oracle expert Tom Kyte—click on the "Registration" link on XE's Database homepage.
News
New Oracle Application Express (Oracle APEX) Packaged Applications AvailableOracle APEX 3.0 compatible applications, including Customer Tracker, Knowledge Testing, and Timesheets, are now available for download. If you are running Oracle XE, you will need to upgrade to the 3.0.1 release.
Oracle Application Express 3.0.1 released; allows upgrade from Oracle APEX version 2.1 in XE
Directions Magazine: Oracle Database XE and Geospatial Information Systems at Farallon Geographics (April 2007)
Independent Software Vendors Embrace Oracle Database 10g Express Edition
International Developer reviews XE: "It allows developers to easily grow and support their applications and data needs over time"
Forrester: Oracle Application Express Helps Build Web Applications Quickly
Developer.com Reviews Oracle Database XE: "An extremely good product"
Oracle Database XE named "Best Database Solution" by LinuxWorld Magazine
Background Information
FAQ
Data Sheet (PDF)
When to Upgrade - FAQ (PDF)
Oracle Database XE and Application Express
Podcast - Tom Kyte on Oracle Database 10g Express Edition (19 min.)
Technical Article - Oracle Database 10g Express Edition: Not Just for Learners
Oracle Magazine News - "Oracle Offers Free Starter Database"
Sample Book Chapters from Hands-On Oracle Database 10g Express Edition (Oracle Press) - Windows Edition Linux Edition
Getting Started
Getting Started Guide
Online Self-Study Tutorial
Oracle Application Express OBE Tutorial