All the English subtitles are captioned professionally. Typically, new content is captioned 2-4 weeks after being added to the site. If you see a video without captions, we recommend waiting for the English captions to be available. If you still would like to create subtitles, and create your own captions, that’s fine too. We note that creating captions without the English baseline available is more time-consuming, and requires that you are familiar with the Khan Academy Captions Standard Guide.