The HTML <th> headers attribute is widely supported across modern web browsers. This attribute is used to explicitly associate a table header cell (<th>) with one or more data cells (<td>) or other header cells (<th>) by referencing their id attributes. This is primarily for accessibility purposes, assisting screen readers and other assistive technologies in understanding complex table structures.

Note: While the headers attribute is crucial for accessibility, it typically has no visual effect on how the table is rendered in standard web browsers. Its impact is primarily on how assistive technologies interpret and convey the table's structure to users.