why do we need express express.Route? code example

Example 1: express route parameters

Route path: /users/:userId/books/:bookId
Request URL: http://localhost:3000/users/34/books/8989
req.params: { "userId": "34", "bookId": "8989" }

Example 2: express route parameters

app.get('/',function(req,res)
{
    res.send("Route path at base address");
});