> There does not seem to be an exact definition that I could find.
From the regulation, Article 3:
1. An undertaking shall be designated as a gatekeeper if:
(a) it has a significant impact on the internal market;
(b) it provides a core platform service which is an important gateway for business users to reach end users; and
(c) it enjoys an entrenched and durable position, in its operations, or it is foreseeable that it will enjoy such a position in the near future.
2. An undertaking shall be presumed to satisfy the respective requirements in paragraph 1:
(a) as regards paragraph 1, point (a), where it achieves an annual Union turnover equal to or above EUR 7,5 billion in each of the last three financial years, or where its average market capitalisation or its equivalent fair market value amounted to at least EUR 75 billion in the last financial year, and it provides the same core platform service in at least three Member States;
(b) as regards paragraph 1, point (b), where it provides a core platform service that in the last financial year has at least 45 million monthly active end users established or located in the Union and at least 10 000 yearly active business users established in the Union, identified and calculated in accordance with the methodology and indicators set out in the Annex;
(c) as regards paragraph 1, point (c), where the thresholds in point (b) of this paragraph were met in each of the last three financial years.
Thanks for digging that out. That's a good expansion of what I meant by 'dominant platform' really, it's just to me, in what I see, that's not the way 'gatekeeper' is used (in the popular modern way, nor does it make sense at all in a metaphorical to historical/literal way). People seem to disagree :shrug:.
From the regulation, Article 3:
1. An undertaking shall be designated as a gatekeeper if:
(a) it has a significant impact on the internal market;
(b) it provides a core platform service which is an important gateway for business users to reach end users; and
(c) it enjoys an entrenched and durable position, in its operations, or it is foreseeable that it will enjoy such a position in the near future.
2. An undertaking shall be presumed to satisfy the respective requirements in paragraph 1:
(a) as regards paragraph 1, point (a), where it achieves an annual Union turnover equal to or above EUR 7,5 billion in each of the last three financial years, or where its average market capitalisation or its equivalent fair market value amounted to at least EUR 75 billion in the last financial year, and it provides the same core platform service in at least three Member States;
(b) as regards paragraph 1, point (b), where it provides a core platform service that in the last financial year has at least 45 million monthly active end users established or located in the Union and at least 10 000 yearly active business users established in the Union, identified and calculated in accordance with the methodology and indicators set out in the Annex;
(c) as regards paragraph 1, point (c), where the thresholds in point (b) of this paragraph were met in each of the last three financial years.
https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CEL...
("core platform service" is explicitly defined to include social networking services)