It can be anything! An apex, subdomain, or even a URL.

Results for*.twitcorp.com

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2021-06-23T09:18:55.641	2021-05-17T00:00:00	2022-05-17T23:59:59	twitcorp.com	*.twitcorp.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2021-06-23T09:18:55.641	2021-05-17T00:00:00	2022-05-17T23:59:59	twitcorp.com	*.twitcorp.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2021-05-17T17:17:37.897	2021-05-17T00:00:00	2022-05-17T23:59:59	twitcorp.com	*.twitcorp.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1
2021-05-17T17:17:37.897	2021-05-17T00:00:00	2022-05-17T23:59:59	twitcorp.com	*.twitcorp.com	C=US, O=DigiCert Inc, OU=www.digicert.com, CN=Encryption Everywhere DV TLS CA - G1