It might be helpful to know generally what these data types are used for:
- binary - is for storing data such as images, audio, or movies.
- boolean - is for storing true or false values.
- date - store only the date
- datetime - store the date and time into a column.
- decimal - is for decimals.
- float - is for decimals. (What's the difference between decimal and float?)
- integer - is for whole numbers.
- primary_key - unique key that can uniquely identify each row in a table
- string - is for small data types such as a title. (Should you choose string or text?)
- text - is for longer pieces of textual data, such as a paragraph of information.
- time - is for time only
- timestamp - for storing date and time into a column.
I hope that helps someone! Also, here's the official list: http://guides.rubyonrails.org/migrations.html#supported-types
