This example demonstrates D3’s selection and data-join mechanism. It maps an array of five numbers to paragraph elements, appending each value as text. Paragraphs whose data values exceed 15 are then filtered and styled with red, bold text using D3's `.filter()` method. The code uses `d3.select`, `.selectAll`, `.data`, `.enter()`, and `.append()` to bind the array and create the DOM nodes, with styling applied via `.style()`.