Why should I use document based database instead of relational database?

Question

Why should I use document based database like CouchDB instead of using relational database. Are there any typical kinds of applications or domains where the document based d

Answer 1

Use a document-based database when you do not need to store data in tables with uniform sized fields for each record. Instead, you have a need to store each record as a document that has certain characteristics. Any number of fields of any length can be dynamically added to a document at any time without the need to "modify the table" first. Fields in document-based can also contain multiple pieces of data.