You can see these MeSH hierarchies in the MeSH Database . The database allows you to:

• Locate and select MeSH terms (Headings, Subheadings, Supplementary Concept Records, and Publication Types) for use in PubMed searches
• See the definition and other helpful information for a MeSH term
• Locate the date when a term was first used for indexing
• See the position of MeSH terms in the hierarchy
• Select MeSH heading/subheading combinations to build a PubMed search

As an example, view the MeSH Database page for the term Neoplasms (https://www.ncbi.nlm.nih.gov/mesh/68009369 ). We will explore using the MeSH Database in more detail in later modules, but for now, just be aware that there is a tool to help you explore MeSH terms.