The fishing license requirements are different for every jurisdiction and oftentimes different depending on the type of fishing you may be doing. Some countries may have one uniform fishing law covering the entire country. In the United States, each state determines its own fishing license policies, when they are required, and who may be exempt.
There are two main types of fishing licenses. Most people are familiar with the recreational fishing license. It is the one needed simply to enjoy a day on the water with a fishing pole and bait. The other type, the commercial fishing license, is used by those who depend on fishing for their livelihood. As such, this license is primarily used for salt water fishing.
Some jurisdictions may allow those under a certain age and over a certain age to fish without a license. This is seen as a way to introduce young people to the sport and give seniors a break. The age restrictions are very commonplace among all jurisdictions, though exact ages may vary from location to location.
Other exceptions to the fishing license requirements may also be in place. For example, some jurisdictions say fishing waters located in one's own county with a certain kind of pole, such as one without a reel, does not require a fishing license. This is to allow those who wish to fish for food to do so without the burdensome requirements of buying a license.
In the United States, those fishing border waters, or those lakes and rivers between two states, usually will only need a fishing license in one state or the other. This is a good benefit. It does not matter which shore you are fishing, or even if you are fishing in backwaters of the neighboring state; the license is just as valid.
For those who wish to fish in a state they do not reside, a fishing license will nearly always be required. Out-of-state fishing licenses are usually substantially more expensive than the rate charged for state residents, though each individual state varies. Due to this fact, proof of residency will usually be required before obtaining a license.
It is up to each individual angler to know what the laws are for the state in which they are fishing. These can often be easily found at access to public waterways or by checking with a local bait shop. They are also found by checking with each state's department which governs fishing, such as the Department of Natural Resources, as it is called in many locations. Fishing without a license can incur substantial fines.