One of the first questions photographers need to ask before investing in lights is whether or not those lights need to be portable. Studio-based photographers are going to pick up different lighting kits than photographers that need to not only easily carry the lighting gear far from any electrical outlet.
A speedlight or flash is often the best photography lighting that’s on-site because of the portability. With an off-camera wireless flash system, speedlights can do much of the work of studio strobes. Wedding and sports photographers tend to favor speedlights because of that portability, as well as the flexibility since the same light can also be mounted on-camera. Speedlights aren’t perfect though. They don’t reach as far as studio lights or light stands, the light isn’t as strong and they can take longer to be ready for that next flash of light. (That last one is a tech spec referred to a recycle time).
Studio style lights are larger, but with battery packs, many of them can be used in the studio or on site. Continuous or strobe lights are significantly larger than speedlights because along with packing the actual light, many require separate battery packs to bring along as well. But these lights answer many of the negatives of using a speedlight because they offer more power and have faster recycle times.
If you’re leaning towards those studio-style lights, you have another decision to make: strobe lighting or continuous lighting? A strobe light has that traditional camera flash with a quick burst of light, while continuous lights are on all the time. Because strobe lights are only putting out light for a short burst, they tend to be more powerful than continuous lights. When shooting portraits, strobe lighting will also make a subtle difference in the subject’s eyes because the burst of light won’t make the pupils larger, leaving more of the color of the iris in the image.
Continuous lights may be less powerful, but they are often affordable — and a must if you are shooting videos rather than stills. For beginners, continuous lights are often easier to work with because you see the light in real time, rather than adjusting, taking a picture with flash, then adjusting again. (Some strobe lights, however, do have a continuous mode to use while setting up the position of the light). Continuous lights are often popular for product photography.