A flash is a very important tool for a photographer. Most cameras come equipped with a standard flash that will pop up when the camera deems that it's needed. Or, you can hit this button or whatever button your camera might to activate the flash. Photographers with more editorial experience often feel more comfortable with "speedlight" TTL flashes due to their light weight and speed of setup/take down. A hand held flash can have more control than a standard flash that comes with a camera. This flash connects right to the top of my camera like so. And, it will automatically read the camera. The camera will automatically read the flash and it will know that they are working together.Studio flashes have the advantage of significantly more lighting power and many options for light modifications such as soft boxes, snoots, and barn-doors. This can be an advantage when you have a large wedding group to photograph, or when the location calls for some creative lighting to achieve the proper romantic feel. In my experience, time is the scarcest resource at a wedding. For my personal wedding photography, TTL flashes' quick setup and lack of need for extension cords or electrical outlets have proven to be a far greater advantage.