Sqlite3 is an easy to use DBMS available as a library. It is a self contained and server less SQL database engine. Because of its ease of use and small foot print it has become DBMS of choice for low traffic web applications.
Using Sqlite3 with rails is real easy. Grab the binaries from Sqlite3 download page. for windows you will require sqlite-3_5_9.zip and sqlitedll-3_5_9.zip. Unzip these files and add them to your PATH environment variable ( or u can simply put the unzipped files to your ruby/bin directory) and you are ready. All Sqlite3 functionality is accessible via sqlite3.exe which you just unzipped and added to path.
To use sqlite3 with rails install sqlite3-ruby gem using gem command. Finally you will need to specify sqlite3 as the connection in the database.yml file of your rails application. Given below is development section of a sample database.yml
Notice that there is no username or password fields as they are not required.
When you do rake db:migrate database file will be created if not already exists.
Note: as of rails 2.0 sqlite3 is the default database and you will need to -d command line option when creating a rails application using to change it or you will need to change database.yml manually.