Indexed journals are considered to be of higher quality in comparison to any non-indexed journals. Indexed journals enjoy better visibility and accessibility.
The h-index is an author-level metric that was invented in 2005 by Jorge Eduardo Hirsch, an Argentine-American professor of physics at the University of California, San Diego.
The h-index was developed by J.E. Hirsch and published in Proceedings of the National Academy of Sciences of the United States of America 102 (46): 16569-16572 November 15 2005. It reflects the productivity of authors based on their publication and citation records.
It indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. the Google Scholar index includes most peer-reviewed online academic journals and books, conference papers, theses and dissertations, preprints, abstracts, technical reports, and other scholarly literature, including court opinions and patents from academic publishers, professional societies, online repositories, universities, and other websites. This estimate also determined how many documents were freely available on the web.