There is not really a single universally accepted definition of "Big Data". What comes closest is the definition in Wikipedia:

"data sets that are so large or complex that traditional data processing applications are inadequate"

And the other on is the one that is pushed by IBM and distinguishes several relevant dimensions (or V's) that justify calling datasets "big data" if they are more of a problem than usual: (1) Volume, (2) Velocity, (3) Variety, (4) Veracity and (5) Value.

So it is not just the size of the datasets that matters, but also what you want to do with it. The number would be different for example if you talk about just storing data, or actually indexing and querying that data, integrating the dataset with other datasets or doing complex data mining on the dataset. For all these different activities the problems with traditional databases start at different sizes, and actually even that is a gross oversimplification because it might even differ per machine-learning algorithm and type of query, at what size you run into trouble with traditional data processing techniques.

So, you know, it depends. :-)

the processed data is information. Information may be data for further processing. So the data or information in the size of peta byte or zeta byte may be big data. If the information is in high volume, velocity and verity is termed as big data

I totally agree with Mr. Hidders. It is not about Volume that makes Big Data really big. Other factors like Velocity, Variety and Veracity must be taken into account in order to consider some data as Big Data. An recently Value which focuses on Data Analytic and making the most of gathered data. Following is link to an infographic by IBM, showing 4 Vs.

http://www.ibmbigdatahub.com/infographic/four-vs-big-data

Yes, there are already many companies that have their own Big Data database systems containing huge amounts of information downloaded from the Internet.

The issues of the use of information contained in Big Data database systems for the purposes of conducting Business Intelligence analyzes are described in the publications:

https://www.researchgate.net/publication/323244120_The_Big_Data_technologies_as_an_important_factor_of_electronic_data_processing_and_the_development_of_computerized_analytical_platforms_Business_Intelligence

https://www.researchgate.net/publication/327035102_The_Technological_Solutions_Big_Data_and_the_Importance_of_Business_Analysis_According_to_the_Business_Intelligence_Formula

I invite you to discussion and cooperation. Greetings

Many companies work towards the huge storage of data. Perhaps the requirement of all those data are unsorted or unstructured. It is used depending on their requirement and purpose.