Prefix Purpose & Functionality

Question

What function do vendor prefixes serve in the code below? Do they call capabilities from other sites?

display: -webkit-box;
display: -ms-flexbox;
display: flex; /* works with row or column */
-webkit-box-orient: horizontal;
-webkit-box-direction: normal;
    -ms-flex-direction: row;
        flex-direction: row;
-webkit-box-align: center;
    -ms-flex-align: center;
        align-items: center;
-webkit-box-pack: center;
    -ms-flex-pack: center;
        justify-content: center;