What is a Database?
Most data saved in a computer will automatically stored in a database. According to David M. Kroeke, database is a self-describing collection of organized information. "self-describing" means there is a particular item which job is to describe information in a database; that item is called Metadata. Thus, database includes not only information, relationship, and tables but also metadata that help defining those information. Here is a link to have more detailed information about database: Database. In addition, underneath this paragraph, there is a video which provide you a brief lecture of database.
What is Metadata?
Usually, metadata, also known as metacontent, is defined as data inside another data. It functions as a tool that describes a particular data of which metadata locates inside. Usually, information stored in a database has its own metadata. Metadata contain all information about the data. Suppose there are an image and word document records stored in a computer database. each record contains its individual metadata. Metadata of the image file has a function to identify the size of the file, folder name at which it is located, color contrast, and any additional information stored in the file. Meanwhile, metadata in word document can identify message on length of the document, date, type of font used, number of characters used, and file type. metadata registry and metadata respository are two names of a metadata that can be kept in a database as inventory.
Aside from database, metadata can also be found in the other forms, such that in photograph, video, and webpage. On the photograph, metadata is constructed into a computerized formation and has a function to determine the information stored by those images. For example, metadata could define picture size, pixels, resolution, color usage, pattern, theme, text stored in the image, and image album's name. Hence, metadata consist of all the information stored by the data. Wikipedia also noted the fact that metadata on the photograph can be coded by camera itself or by photographer and/or particular software once those pictures were being uploaded in the computer.
Sourced from Wikipedia, there are several divisions of metadata. NISO identifies that there are three types of metadata; they are structural metadata, administrative metadata, and descriptive metadata. Structural metadata is an information that define how objects and application software within a system are organized properly. Basically, it performs as identifier and indicator to ensure that objects within a system are bounded logically. It holds the relationship and association within and among objects. Just like its name, administrative metadata has a function at which it display only information useful for organizing the main data. Document type, size of the record, date modified and created, and author are types of information displayed by administrative metadata. Administrative metadata is classified further into two categories, which are rights management metadata and preservation metadata. Right management metadata is more about demonstrating information relative to the management of intellectual property right's data. Unlike right management metadata, preservation metadata tend to incorporate information which is used to identify data stored in a system. The information used as a base to find a specific data is called descriptive metadata. Title, abstract, author, subjects, keywords, and publisher are typical keywords utilized by descriptive metadata (Wikipedia, 2011).
Aside from NISO, Bretheron & Singley had also classified metadata into two forms, which are structural metadata and guide metadata. For the structural metadata, Bretheron & Singley had exactly the same definition as NISO at which structul metadata is used as an information that define and portrays organization among and/or within the objects and application softwares. Contradictorily from structural metadata, guide metadata is more to assisting users in finding their specific inquiry in regards to a data/ resources. The results usually comes out as set keywords or in the form of conversational language which can be easily understood by human being.
Moreover, Ralph Kimball also categorized metadata into three divisions; those are technical metadata, business metadata, and process metadata.
Through the explanations about metadata and its divisions, I conclude that metadata is a data which function is to define the other data. The process of defining the data is supported by the theory of each of metadata's division. Descriptive metadata help users discovering a particular data. Basically, it filters requested data and unwanted one. In addition, it describes a specific object and/or data in a computer system. Not only providing service in defining the information and objects, as mentioned by structural metadata, metadata can acts as an identifies by providing information about structural condition of a system. Furthermore, metadata can also act an adviser who guides the user into their destination. Guide metadata help provide guidance in the form of human language. Finally, through administrative metadata, metadata can be an administrator whose job is to organize the data.