What is Database ?

Many sites provide you information as collection of data is database.

Let me explain the same in detail with an example to be more clear.

Name is data , the place he lives is another data,his phone number is another data ,etc.So now if I combine all thisat one then it again called as set of data.Similarly say Item Description is another data,Item quantity is another data,etc.So this would be again 1 more set of data.
So these sets of data i.e. these sets or collection of data is called as database.

Now lets come to what all forms we can store this data. We can store this data in a text file, excel file,word file,etc.So what would be the difference between storing the same in above files and storing it in RDBMS like SQL,Oracle,DB2,for which look for the article what is RDBMS