Speedlite camera flash units enable you to add extra light to a scene and take control of how your subject is illuminated. They're useful in low-light conditions but they can also transform images in bright sunny conditions by filling in shadows and helping to balance the exposure across the scene.
Canon has a range of Speedlites to suit different cameras, photographers and shooting situations. For example, the Speedlite EL-1 is very powerful and well-suited for use on pro cameras such as the Canon EOS 5D Mark IV or full-frame mirrorless EOS R5, whereas the Speedlite EL-100 is very compact and more at home on a smaller camera like the EOS 250D or compact mirrorless EOS M6 Mark II. And for macro photography, there's the Macro Ring Lite MR-14EX II and Macro Twin Lite MT-26EX-RT, which help you get light onto very close subjects.
All Speedlites have a collection of Canon technologies to help you get the best possible results, and it's useful to understand a bit about them to ensure that you select the right Speedlite and get the best from it. So here's a guide to the most important Speedlite basics.