There are several forms of defense against an angry bear, but only two that are consistently practical or effective. Ideally, a person will never find themselves in that type of a situation. The best way to avoid tragedy with an angry bear is to never get into a situation with an angry bear, but in all fairness there are probably very few times in history where someone went out just itching for a fight with a predator that is a little bit further up the food chain...sometimes quite literally despite our technological edge.
There are plenty of YouTube videos about bear proof suits, but all of that junk is impractical and fairly useless when common sense is applied to everything. If a person is serious about protecting themselves from bears, there are two options: bear spray and bear guns.
Bear spray is normally the best option. While many people who haven't had to deal with the big mammals find this unbelievable, the truth is that bear mace is much stronger than mace, and is illegal for use against people in most states because of how powerful it is. Studies have shown, as well as many real life reports from incidents with bears, that the bear spray is effective in deterring an attack over 95% of the time - and that percentage is far higher than the percentage of people who get away unharmed after using a firearm. Keep in mind that while a bear is bigger and stronger than a person, their nose is also 10,000 times as sensitive-making bear mace amazingly effective in deterring even the angriest bears.
The other option is going with a bear gun. A bear gun is a general term, and most people who live in areas like Alaska are referring to either a 12 gauge shotgun, or any handgun that is larger than a .357 Magnum. In the case of a handgun, .357 Magnum and .44 Magnum are the most common types. Be aware that handguns are not easy to fire accurately, and these handguns have a huge kick, making them even harder to master. Anyone who is going to go this route had better make sure they are proficient with the firearm.
These are the main ways to defend yourself from possible bear attacks in the wild.