What is SCI journal abbreviation?

Could you please explain what the abbreviation "SCI" stands for in the context of academic journals? I'm interested in understanding how it relates to the field of science and the publication process. Specifically, I'm curious about how SCI journals are evaluated and the criteria used to determine their status as a high-quality source of scientific research. Could you elaborate on this and provide any insights into the importance of publishing in such journals for researchers?