The key-value pair in a schema is called a path. Paths define the name and type of fields in a MongoDB document.

const poemSchema = new mongoose.Schema({
  title: String,
  body: [String],
  published: Boolean,
})

The schema above has three paths: title, body, and published. Each path is set to a different schema type. The [String] schema type, assigned to body, means a document that is derived from the poemSchema schema can store an array of strings to the body field.

Paths in Mongoose can have many data types. Besides data types like string, integer, boolean, and array, Mongoose also provides:

• Timestamp − timestamp. This can be handy for recording when a document has been modified or added.
• Object ID − This datatype is used to store the document’s ID.