There are two kinds of photographs with respect to the significance of their use of colours. On the one hand, ever since colour film technology became widely available, colour has become the default in most photographic practices. That is, some photographs are in colour not because their colours bear some special significance (compared, for instance, to their possible black and white counterparts) but simply because the available film or digital technology has long made colour the common method of capturing photographic images. We may think of these photographs as colour by default. On the other hand, colours are often central to the meaning of photographs for their emphatic, symbolic, psychological, social, compositional, etc. significance. These photographs would not work in black and white the same way, or they would not work at all. That they are in colour is not merely a technological given; rather, it is an integral, formative, and significant aspect of their photographic meaning. We may think of these photographs as colour by significance.