Are all journals indexed by Google Scholar automatically peer-reviewed, and what role does an ISSN play in confirming peer review status?

No, not all journals indexed by Google Scholar are automatically peer-reviewed. Google Scholar is a broad search engine for scholarly literature and includes various types of publications, some of which may not undergo formal peer review (e.g., preprints, theses, some conference proceedings). While an ISSN identifies a serial publication, it does not inherently guarantee peer-review status. To confirm if a journal is peer-reviewed, one typically needs to check the journal's official website, its 'About Us' or 'Instructions for Authors' sections, or consult databases like Ulrichsweb which often indicate peer-review status. The ISSN helps identify the journal, but external verification is needed for peer-review confirmation.