What is Notability (Wikipedia)?
Short answer
Wikipedia’s standard for whether a subject deserves an article: significant coverage in multiple reliable, independent, secondary sources.
Companies are judged under WP:NCORP, people under WP:BIO. Both require coverage that is independent of the subject, meaning not written, placed or paid for by them.
Press releases, sponsored articles, interviews that simply repeat what you said, routine funding announcements and churnalism are all explicitly discounted. This surprises people who have spent heavily on coverage.
Why it matters
It is the single reason most Wikipedia attempts fail, and the reason buying placements to qualify usually does not work.