Ever since we started releasing home-brewed Firefox extensions here at Lifehacker, several readers have asked: How difficult is it to build a Firefox extension? For someone with a bit of programming experience, the answer is not that difficult. The meat of a Firefox extension is simply Javascript - the not-very-mysterious stuff of bookmarklets and regular old web pages - and a markup language call
![How to build a Firefox extension](https://cdn-ak-scissors.b.st-hatena.com/image/square/ede80190844f3581a47b50bb28cbe8c695358cfa/height=288;version=1;width=512/https%3A%2F%2Fi.kinja-img.com%2Fgawker-media%2Fimage%2Fupload%2Fc_fill%2Cf_auto%2Cfl_progressive%2Cg_center%2Ch_200%2Cq_80%2Cw_200%2Fu0939doeuioaqhspkjyc.png)