Pre-print papers are research papers shared publicly before they undergo formal peer review. They are usually deposited on preprint servers such as arXiv, bioRxiv, or medRxiv and are accessible for free. Pre-prints are common in fields like computer science, physics, and biology, where researchers want to disseminate their findings quickly and receive early feedback from the scientific community.

Peer review is a process where submitted papers are evaluated by independent experts in the field (peers) before being accepted for publication in a journal. This process helps ensure the validity, significance, and originality of the research.

Peer Review Process:

1. Submission to a Journal: After writing the paper, researchers submit it to a journal.
2. Initial Screening: The journal’s editorial board screens the paper for relevance and quality.
3. Peer Review: If the paper passes the initial screening, it’s sent to experts in the field who evaluate it for scientific accuracy, methodology, and contribution to the field.
4. Feedback and Revisions: Reviewers may suggest revisions, or the paper could be accepted, rejected, or sent back for major revisions.
5. Publication: Once the paper passes peer review, it is published in the journal.

Where Do Papers Go After Peer Review?

After passing peer review, papers are typically published in academic journals. These journals can be either:

• Open access: Papers are freely available to the public (e.g., PLOS ONE).
• Subscription-based: Papers are accessible behind a paywall, available only to subscribers or institutions that purchase access (e.g., Nature, Science).

How to Know If a Paper Has Been Peer Reviewed:

1. Journal Information: Look up the journal where the paper was published. Most reputable academic journals clearly state that they are peer-reviewed in their "About" or "Submission" sections.
2. Check Indexing: Peer-reviewed journals are often indexed in databases like:
   • PubMed (for biomedical research)
   • IEEE Xplore (for engineering and computer science)
   • Scopus
3. Cross-referencing with Pre-print Databases: If a paper is available on a preprint server (e.g., arXiv), check if it has been marked as "under review" or "published" with a link to its final version in a journal.
4. Search for Peer-Reviewed Labels: Websites like Google Scholar or Semantic Scholar often mark papers as peer-reviewed once they are published in a journal.
5. DOI (Digital Object Identifier): Many peer-reviewed journals assign DOIs. Searching the DOI of a paper in databases like CrossRef can reveal its peer-review status.

Differences Between Pre-print and Peer-Reviewed Papers:

• Pre-print papers:
  • Publicly accessible without peer review.
  • Useful for sharing findings quickly.
  • May have errors or unverified claims.