How do I handle file uploads via $_POST in PHP?

Handling file uploads via $_POST requires setting the correct enctype and using the $_FILES array:

<form method="post" action="upload.php" enctype="multipart/form-data">
    <input type="file" name="file">
    <input type="submit" value="Upload">
</form>

In upload.php, process the uploaded file using $_FILES:

<?php
if ($_SERVER["REQUEST_METHOD"] === "POST") {
    if (isset($_FILES["file"]) && $_FILES["file"]["error"] === UPLOAD_ERR_OK) {
        $tmp_name = $_FILES["file"]["tmp_name"];
        $name = $_FILES["file"]["name"];
        move_uploaded_file($tmp_name, "uploads/" . $name);
        echo "File uploaded successfully";
    } else {
        echo "File upload failed";
    }
}
?>

Ensure the uploads directory is writable and handle errors appropriately.