Now, whatever we're adding to our unknown sample, it's called a titren, and a titrate be their base or an acid. So let's illustrate Titration using a picture and then a graph. So suppose we have some known volume of acid, say, I don't know, hydrochloric acid in our flask, and we have a PH reader attached to the inside of our flask. So at any given time, we could measure our PH. Now suppose we have some known concentration of base and we begin adding this base drop by drop. Now, before we add the base, our PH is say, I don't know, two.