There is great article on this website that explains in simple terms what alkalosis and acidosis is and how it can occur:
Being able to test your pH is very helpful and almost necessary especially if you are striving for that optimal level and the best overall health.
The most accurate way to check your pH is at the doctors office with a blood pH test, however this is not really convenient for most of us and would probably end up being expensive if checked regularly. Not only this, most places you have to wait for blood results.
SO.. Your next step, which is the most commonly used way is with testing strips that you can use for saliva and/or urine. Saliva testing tends to be a little bit more acidic than your blood test and urine testing can vary since your urine pH tends to fluctuate throughout the day. But overall you will get a close enough result.
The testing paper usually comes in a roll that you can just tear off and use. The paper will turn a different color according to what your pH is and you will just match it to the color scale they have on the box or container. Amazon has a bunch of different brands of testing strips at affordable prices! I just love Amazon :)