BidRequest.imp

The array of Imp objects, one per impression on offer. Required, with at least one entry.

Currentobject arrayRequiredSince 2.0

Field facts

Path: imp
Object: BidRequest
Type: object array
Requirement: Required
Added: OpenRTB 2.0
Spec section: 3.2.1

How it is used

Each Imp has its own ID, floor, and one or more media objects (banner, video, audio, native). Bids point at an impression through Bid.impid. Offering several impressions in one request lets a seller sell every slot on a page at once, which BidRequest.allimps and SeatBid.group build on.

Example

Where the field sits in a payload, with everything else left out:

{
  "id": "req-1",
  "imp": [
    {
      "id": "1",
      "banner": {
        "w": 300,
        "h": 250
      },
      "bidfloor": 0.5,
      "bidfloorcur": "USD"
    }
  ]
}

Common mistakes

An empty imp array. The request offers nothing and fails validation.
Duplicate Imp.id values within one request make bids ambiguous.
Sending a single Imp object instead of an array.

Version history

Added in OpenRTB 2.0, and present in the latest snapshot. The table shows how each version's spec text types the field.

Versions	Type in the spec	Required	Deprecated
2.0 to 2.2	array of objects	Yes	No
2.3 to 2.6-202606	object array	Yes	No

Related fields

Other BidRequest fields

For a walkthrough of the whole object, read Bid request anatomy.