Sadly, there is a lot of misinformation out there about pH and what is does to your aquarium and the fish in it. There are a lot of pet stores, websites, sales people and fish owners that will tell you that you cannot be a responsible fish owner unless you are always worried about the pH levels of your fish tank. The simple fact of the matter is that a lot of fish are perfectly capable of living in various pH levels, as they do in nature. There are only a few types of fish out there that require more specific pH levels and since these are not a beginner's fish, you should not have to worry about this. The worst that could happen for your fish is that they will not spawn new fish. So, if you are not into breeding fish, then you should not have to put too much into worrying about pH levels.
Another thing that you are going to want to remember is that often times, when someone starts messing around with the pH level of the water in their fish tank, the open up Pandora's box. Add anything new to that aquarium, such as some gravel, a new decoration, your hand or even some nice fish food and the pH levels could rise up or fall down extremely fast. You are going to find yourself trying to play scientist while adding all sorts of chemicals into the water your fish were enjoying, when it really was not needed in the first place.
Even though you might now realize that you are not going to need to play around with the pH levels, you still might be interested in just what pH is. Understanding what it is and what is means is certainly a lot easier to get then trying to figure out how to control it. Basically, pH is a measurement of how alkaline or acidic the water is. There is a measurement scale that goes from 1 to 14. The lowest point, is 1, with the highest point being 14 and 7 is the obvious "neutral" point. Anything that has a pH lower than a 7 is considered acidic. Anything that has a pH that is higher than 7 will be considered basic.
Again, the pet industry, who claims to simply want to inform fish owners how to properly care for their fish, will tell you that you must keep the pH level at 7. They will advise you to purchase anything and everything in order to make sure that you are turning your kitchen into a laboratory while you try to juggle pH balances. In nature, most of the fish that you would be dealing with, survive in waters that have various pH levels. Generally, the pet industry is just telling you otherwise in order to convince you to purchase their wide array of chemicals. After all, if they don't convince you of a reason, they can't make any money.