The simplest definition of metadata would be – metadata is data about data. This metadata might be about the kind of underlying data or the structure in which underlying data is stored or some description of the underlying data or some other aspect of the underlying data. Metadata may be saved in the original file itself, or may be stored elsewhere in some other file or a location.
The best example in explaining metadata would be a photograph. Although you may see only a photograph when you open one, the file actually contains much more data about the photograph, e.g. the data and time when photograph was taken, the place where the photograph was taken, the details of camera used, the dimensions of the photograph, etc. This helps in better organization and management of photos. Another example might be the call-log on your mobile phone with respect to the calls you make. The call log will tell you with whom you have talked over phone, but it will not tell you what talks you had. Similarly, metadata about other files will tell you more details about the underlying data.
But since metadata isn’t actually the data, is it important? Yes it is important, and sometimes equally important as data since sometimes the nature and patter of underlying data is as important as the data itself.
Some of the uses of metadata can be as follows:
- It can give insights about the underlying data – e.g. Email headers contain lot of important data about an email including sender’s IP address. Even if you encrypt your email content, the metadata may reveal hidden details.
- It can be used to classify data into various categories – e.g. Tags ascribed to a file may be used to categorize the data.
- It can also provide context of the data – e.g. The basic fact that you are buying baby clothes on a website may mean that you are expecting a baby. Thus, you may be shown advertisements related to other baby products.
- It can help in inter-operability of different applications using the same underlying data and thus metadata can help in sharing of data.
- In case you have an online website, search engines rate or show your website in results depending upon the metadata of the website. This is what is used in Search Engine Optimisation.
Metadata is an important ingredient of online privacy, and it should be managed well – online and offline.
For Wikipedia entry on Metadata, click here.
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