Impact Factor is a quantitative metric for evaluating, comparing, and ranking scientific journals in different fields at the national or international level.
Journal Indexing helps maintain the ethics and quality in terms of publication and increase visibility, validity, availability, and readership of a paper.
Indexed journals are considered to be of higher quality in comparison to any non-indexed journals. Indexed journals enjoy better visibility and accessibility.
The purpose of ISI is to increase the visibility and ease of use of open access scientific and scholarly journals. If your journal is indexed & got validated stamp from ISI, you can request for the calculation of impact factor for your journal.