There's been relatively little gold exploration in the last few years, but John Kaiser of Kaiser Research believes that may be set to change. "I think we're going to see a shift back to discovery exploration as opposed to simply feasibility demonstration," he says in the video above.If that happens, there will be plenty of opportunities for investors to profit. But which gold exploration companies are poised to do the best? According to Kaiser, one thing investors can do to help narrow the field is to gain an understanding of the different types discovery exploration."Cover all the bases, place bets on these different styles. The key is to understand ... the strategy behind [each] junior, and give yourself exposure to a number of them," he explains.For instance, some companies are doing traditional exploration, while others are using new technology to take a different approach to the exploration process. Still others are returning to old districts with new ideas on how to make them profitable once again.Watch the video above to hear Kaiser explain those types of exploration and give examples of gold juniors that are using each style. He also discusses gold juniors with optionality and what Donald Trump's presidency could mean for commodities.You can also skip directly to different parts of the interview:0:20 - Trump's potential impact on commodities3:21 - types of discovery exploration6:12 - traditional exploration (Rainy Mountain Royalty (TSXV:RMO))9:12 - new technology (San Marco Resources (TSXV:SMN), Nevada Exploration (TSXV:NGE))14:10 - rethinking old districts (Adamera Minerals (TSXV:ADZ))16:46 - optionality (Midas Gold (TSX:MAX))21:56 - what should investors focus on? (Skeena Resources (TSXV:SKE))