Here are some key points on why peer review is essential before sending the manuscript to the journal or publisher:

1. Quality assurance: Peer review provides an objective assessment of the manuscript's quality, ensuring that it meets the required standards for publication.

2. Identification of flaws: Peer review allows subject matter experts to identify and address any weaknesses in the manuscript, such as errors in methodology, data analysis, or interpretation.

3. Improvement of content: Peer review helps improve the overall content of the manuscript by providing feedback on its clarity, coherence, and relevance.

4. Ensuring accuracy: Peer review helps to ensure that the manuscript is factually accurate and that the references cited are appropriate and up-to-date.

5. Increasing credibility: Peer review adds credibility to the manuscript and the author, as it demonstrates that the work has been evaluated and approved by experts in the field.

6. Meeting journal requirements: Peer review helps ensure that the manuscript meets the specific requirements of the targeted journal, such as formatting, length, and writing style.