Definiton of IVT as per the Media Rating Council (MRC) Guidelines &  TAG (Trustworthy and Accountability Group)

IVT is Invalid Traffic

Traffic that does not meet certain ad serving quality or completeness criteria, or otherwise does not represent legitimate ad traffic that should be included in measurement counts. Among the reasons why ad traffic may be deemed invalid is it is a result of non–human traffic (spiders, bots, etc.), or activity designed to produce fraudulent traffic.

General Invalid Traffic (GIVT)

Traffic identified through routine means of filtration executed through application of lists or with other standardized parameter checks.

Key examples are:

1. Known data–center traffic (determined to be a consistent source of non–human traffic; not including routing artifacts of legitimate users or virtual machine legitimate browsing)

2. Bots and spiders or other crawlers (except those as noted below in the “Sophisticated Invalid Traffic” category)

3. Activity–based filtration using campaign or application data and transaction parameters from campaign or application data

4. Non–browser user–agent headers or other forms of unknown browsers and pre–fetch or browser pre–rendered traffic (where associated ads were not subsequently accessed by a valid user; pre–fetch clicks associated with accessed ads should not be counted until acted–upon by a valid user).

5. Invalid placements (specific to ads); small, barely visible or invisible ad delivery or illogical (non-industry standard) ad size of 0x0 and 1×1 either declared or as delivered on the client side

6. Non-rendering capabilities; sessions or traffic without the capability to render or display images (other than cases of disabled image rendering) even though rendered impressions or other activity may be associated with them such as headless browsers or component devices without a display component. This does not relate to and is agnostic of visibility or viewability of an ad.
illogical (non-industry standard) ad size of 0x0 and 1×1 either declared or as delivered on
the client side;

Sophisticated Invalid Traffic (SIVT)

Situations that require advanced analytics, multi–point corroboration/coordination, significant human intervention, etc., to analyze and identify.

Key examples are:

1. Bots and spiders or other crawlers masquerading as legitimate users; hijacked devices

2. Hijacked sessions within hijacked devices; hijacked ad tags; hijacked creative; hidden/stacked/covered or otherwise intentionally obfuscated ad serving

3. Invalid proxy traffic (originating from an intermediary proxy device that exists to manipulate traffic counts or create/pass–on non–human or invalid traffic or otherwise failing to meet protocol validation);

4. Adware; malware; incentivized manipulation of measurements (fraudulent incentivized promotion of an entity, without its knowledge or permission – excludes cases where the entity paying for the incentive is the entity being promoted**);

5. Misappropriated content (where used to purposefully falsify traffic at a material level); falsified viewable impression decisions

6. Falsely represented sites (sites masquerading as other entities for illegitimate purposes) or impressions; cookie stuffing, recycling or harvesting (inserting, deleting or misattributing cookies thereby manipulating or falsifying prior activity of users)

7. Manipulation or falsification of location data or related attributes; and differentiating human and IVT traffic when originating from the same or similar source in certain closely intermingled circumstances.