What is the need for data representation in computer?

Answer 1

"Data Representation" as you refer to it almost certainly refers to some means of storing data in a form which a program on a computer can find it again.

An example would be a simple text file containing a list of all the people you meet. If for example you were to write every name of every person you meet, all in lower case with no spaces or carriage returns, you have stored the data, but it is likely you'd never be able to read the list again. To represent the data more intelligently, you might start by separating each person with a carriage return. Then you would probably want to capitalize the first letter of each name. Then to cope with names like "McVey", you might add a space in-between each name. After doing all this, you should be able to read the list quite easily. If however you wanted to sort the list, you would be limited to spring just on the whole name starting with the first letter and ending with the last. This is because you have created a singled column of names. Therefore, it might have been better to add more spaces between first and last names in order to have a single column of first names and also a column of last names.

While data representation can be far more complex or advanced than this... For example, XML on the easier side, ASN.1 defined languages on the more complex, or even complex lists describing position, energy and time as would be common for data collected at the Large Hadron Collider, the point is that data is meaningless if there is no way to identify how it is stored in a meaningful way.