It depends upon the indexing company. Some require the satisfying of a defined threshhold (IF; number of published papers per Journal, etc). Others are on a "fee for service" basis. Of course today, the main indexing services are the Web of Knowledge, Scopus, Google Advanced Search, Biol Abstracts, Chem Abstracts, etc. Regardless, indexing services play a major role for the exposure of one's work. For some Universities, acknowledgement of a publication by the University requires indexing in given indexing services (ex: Web of Knowledge). Lastly, the key words of your article are essential for maximum coverage. Therefore, use the maximum provided by the given Journal with prominent indexing service(s). It is therefore important that the indexing services used by a given Journal provide the maximum exposure of your work.
It depends upon the indexing company. Some require the satisfying of a defined threshhold (IF; number of published papers per Journal, etc). Others are on a "fee for service" basis. Of course today, the main indexing services are the Web of Knowledge, Scopus, Google Advanced Search, Biol Abstracts, Chem Abstracts, etc. Regardless, indexing services play a major role for the exposure of one's work. For some Universities, acknowledgement of a publication by the University requires indexing in given indexing services (ex: Web of Knowledge). Lastly, the key words of your article are essential for maximum coverage. Therefore, use the maximum provided by the given Journal with prominent indexing service(s). It is therefore important that the indexing services used by a given Journal provide the maximum exposure of your work.
Dear @Ramana, try to get some answers from this excellent resource from 2015.
Research Evaluation Metrics!
"For research evaluation, some other indicators were needed. Citation analysis along with peer review ensured better judgment in innumerable cases. Something more was needed to make the judgment foolproof to a great extent. The advent of World Wide Web (WWW) provided the opportunity. Quite anumber of indicators have come up based on the data available in WWW..."
Dear @Ramana, I have just received SCOPUS Newsletter. This is good reading about the issue : 4 ways to view and use the 2014 Scopus journal metrics!
"Whether you are an author investigating where to submit your paper, an editor evaluating your journal’s performance or a librarian reviewing the impact of your investments, it is important to know how journals compare to each other. With the 2014 journal metric values for the Source Normalized Impact per Paper (SNIP), SCImago Journal Rank (SJR) and Impact per Publication (IPP) live in Scopus, now is a good time for evaluation and comparison..."