What is “Card” under the Contacts>Lists>iCloud on my iPhone & Mac?

I regret the responses as to “What is card category?" in the contacts weren’t clear to me. So by further looking at the difference between the contacts shown under the categories “card” & “All contacts” I gathered, contact cards are created for contacts which have, not only the name & phone number, but other information like address, email, & notes. That is, if a contact is created with only the name &/or phone number, that contact is not included in the “card” category.

Thanks for the response, however, the explanation you referenced relates only to “My” Card & not a whole group of contacts under that category. So once again: What is “Card” under the Contacts>Lists>iCloud on my iPhone & Mac? Why does this “Card” category include many of "All iCloud” contacts but not all? What is this category, how was it created, & do I need it if a complete list of contacts is available under All iCloud?