A quick look at Jade extends, block, include.

gistfile1.js

// file index.jade
html
    head
        block head
    body
        block content
        

// file view.jade
extends index.jade

block head
    script(src='')
    link(href='')
    
block content
    h1 Hi there!
    include message.jade
    
// file message.jade
p message of the day

// Now if you render view.jade, it includes message.jade, compiles everything, 
// gets index.jade, and places the blocks at the corresponding place.