hCard
hCard is a microformat for publishing contact information of people, companies, and organizations on the web, using HTML or XHTML markup. It allows semantic representation of details like names, addresses, and phone numbers, enabling machines to easily parse and extract this data. This format is based on the vCard standard and is designed to be human-readable while also machine-processable.
Developers should learn hCard when building websites that need to share structured contact information, such as personal portfolios, business directories, or social networking features, as it enhances interoperability and data portability. It is particularly useful for SEO and accessibility, as it helps search engines and assistive technologies understand contact details, and it integrates well with other microformats like hCalendar for events.