For most placer miners, the goal of exploration is finding somewhere to mine so that they can produce gold.
Some people find exploration and prospecting to be the most interesting part of placer mining. If they make a good discovery, they have made the claim more valuable. Their goal might be to sell the claim for more than they paid for it.
Some claim owners pay for trenching - They get great information and when they register the work, the claim will be good for years.
The location of the bedrock can be important in placer mining. What rocks and minerals make up the bedrock is usually not important. Where there are boulders and how rounded they are (how far they have traveled) may be important.
Some creeks have more history than others. We have a claim on Lightning Creek at Wingdam Creek. Now, that's a claim where you can get some history!
A lot of claims get only this kind of exploration.
A shovel and gold pan (and notepad and GPS) are the standard tools.
Some people use gold-detectors - specialized metal-detectors, which can cost a lot - thousands of dollars for some equipment. They are powerful tools.
But there is also a lot to be said for using your brain and a $20 gold pan.
Placer prospecting almost always involves taking and testing samples with a gold pan or sluice box.
Exploration and mining are often combined. Many miners focus on their most promising ground, but also spend some time over the season prospecting and test-mining. Some leads turn into prospects, some get serious test-mining and some become the new "most promising ground".
Trenching and test-mining with a backhoe or excavator or other mechanical equipment requires a permit.
Some placer prospectors do traverses, although they might do them along lines that follow or cross the stream or valley.
If creating a Property Report is one of the goals of exploration, traverses are a good way of collecting information.
Traverses are advised if you want to impress someone with a prospecting report. This includes registering prospecting as technical work to maintain your placer claim or trying to interest a potential backer who might invest in your project.