Search engines, as well as any other computer programs that wants to read such info, look for “microdata” in websites. Microdata is extra information that is written specifically for computers to read rather than humans. Making information available this way means that the computers reading it can understand it without having to rely on surrounding content and other context.
For example, consider the following content you might see on a website:
Acme Insurance Agency
Office 1-800-555-ACME
Fax 1-503-555-1001
It’s easy for a human to look at that and understand that there’s a business name, a phone number, and a fax number. However, a computer has to try to interpret what each of those pieces of information might mean. After all, each one of the numbers could be a phone or a fax number.
Contrast the above with the following:
<script type="application/ld+json">
{
"@context": "https://schema.org",
"@type": "InsuranceAgency",
"name": "Acme Insurance Agency",
"telephone": "1-800-555-2263",
"faxNumber": "1-503-555-1001"
}
</script>
When this type of microdata is available, the search engine can rely on the information it finds within, where it’s clear that the page is describing an InsuranceAgency and that it has a telephone and faxNumber.