Base profile: http://hl7.org/fhir/us/core/StructureDefinition/us-core-encounter

An Encounter is an interaction between a patient and healthcare provider(s) for the purpose of providing healthcare service(s) or assessing the health status of a patient.During the life-cycle of an encounter it will pass through many statuses. Typically these are in order or the organization's workflow: planned, in-progress, finished/cancelled.

Read more from : https://hl7.org/fhir/R4/encounter.html

Sample Response Object:

{
  "resourceType" : "Encounter",
  // from Resource: id, meta, implicitRules, and language
  // from DomainResource: text, contained, extension, and modifierExtension
  "identifier" : [{ Identifier }], // Identifier(s) by which this encounter is known
  "status" : "<code>", // R!  planned | arrived | triaged | in-progress | onleave | finished | cancelled +
  "statusHistory" : [{ // List of past encounter statuses
    "status" : "<code>", // R!  planned | arrived | triaged | in-progress | onleave | finished | cancelled +
    "period" : { Period } // R!  The time that the episode was in the specified status
  }],
  "class" : { Coding }, // R!  Classification of patient encounter
  "classHistory" : [{ // List of past encounter classes
    "class" : { Coding }, // R!  inpatient | outpatient | ambulatory | emergency +
    "period" : { Period } // R!  The time that the episode was in the specified class
  }],
  "type" : [{ CodeableConcept }], // Specific type of encounter
  "serviceType" : { CodeableConcept }, // Specific type of service
  "priority" : { CodeableConcept }, // Indicates the urgency of the encounter
  "subject" : { Reference(Patient|Group) }, // The patient or group present at the encounter
  "episodeOfCare" : [{ Reference(EpisodeOfCare) }], // Episode(s) of care that this encounter should be recorded against
  "basedOn" : [{ Reference(ServiceRequest) }], // The ServiceRequest that initiated this encounter
  "participant" : [{ // List of participants involved in the encounter
    "type" : [{ CodeableConcept }], // Role of participant in encounter
    "period" : { Period }, // Period of time during the encounter that the participant participated
    "individual" : { Reference(Practitioner|PractitionerRole|RelatedPerson) } // Persons involved in the encounter other than the patient
  }],
  "appointment" : [{ Reference(Appointment) }], // The appointment that scheduled this encounter
  "period" : { Period }, // The start and end time of the encounter
  "length" : { Duration }, // Quantity of time the encounter lasted (less time absent)
  "reasonCode" : [{ CodeableConcept }], // Coded reason the encounter takes place
  "reasonReference" : [{ Reference(Condition|Procedure|Observation|
   ImmunizationRecommendation) }], // Reason the encounter takes place (reference)
  "diagnosis" : [{ // The list of diagnosis relevant to this encounter
    "condition" : { Reference(Condition|Procedure) }, // R!  The diagnosis or procedure relevant to the encounter
    "use" : { CodeableConcept }, // Role that this diagnosis has within the encounter (e.g. admission, billing, discharge â€¦)
    "rank" : "<positiveInt>" // Ranking of the diagnosis (for each role type)
  }],
  "account" : [{ Reference(Account) }], // The set of accounts that may be used for billing for this Encounter
  "hospitalization" : { // Details about the admission to a healthcare service
    "preAdmissionIdentifier" : { Identifier }, // Pre-admission identifier
    "origin" : { Reference(Location|Organization) }, // The location/organization from which the patient came before admission
    "admitSource" : { CodeableConcept }, // From where patient was admitted (physician referral, transfer)
    "reAdmission" : { CodeableConcept }, // The type of hospital re-admission that has occurred (if any). If the value is absent, then this is not identified as a readmission
    "dietPreference" : [{ CodeableConcept }], // Diet preferences reported by the patient
    "specialCourtesy" : [{ CodeableConcept }], // Special courtesies (VIP, board member)
    "specialArrangement" : [{ CodeableConcept }], // Wheelchair, translator, stretcher, etc.
    "destination" : { Reference(Location|Organization) }, // Location/organization to which the patient is discharged
    "dischargeDisposition" : { CodeableConcept } // Category or kind of location after discharge
  },
  "location" : [{ // List of locations where the patient has been
    "location" : { Reference(Location) }, // R!  Location the encounter takes place
    "status" : "<code>", // planned | active | reserved | completed
    "physicalType" : { CodeableConcept }, // The physical type of the location (usually the level in the location hierachy - bed room ward etc.)
    "period" : { Period } // Time period during which the patient was present at the location
  }],
  "serviceProvider" : { Reference(Organization) }, // The organization (facility) responsible for this encounter
  "partOf" : { Reference(Encounter) } // Another Encounter this encounter is part of
}

This representation captures the essence of an Encounter resource in FHIR, including relevant patient information, the type and status of the encounter, and the healthcare providers involved.