Any solution for which the concentration is precisely known is called a standard solution.
An acid/base titration uses the fact that one can be "neutralized" with the other. In this neutralization reaction, the acid and base will combine to produce a salt plus water. When done correctly, the resulting solution will be "neutral"  neither acid nor base. In a titration, this is known as the end point. The change in pH of the solution can be monitored using an indicator or pH meter. It is extremely important that the exact amounts of each solution used be known at the end point.
with a strong base 
This graph represents the titration of 10 ml of 0.1M HCl with 0.1M NaOH.
The end point is characterized by a rapid change in pH with very little base added. 
Phenolphthalein is the indicator we will use for an acid/base titration. Add two drops to the acid solution to be titrated. The solution will be colorless at this point. Slowly add the base solution until the faint pink color persists.
At the end point you know the concentration of the standard and the volume used, as well as the volume of the unknown used. Calculations can now be done to compare the number of moles of each solution used. This will give you the concentration of the unknown. 
Phenolphthalein Color Chart
acidic solution. 
neutral solution.  
basic solution. 
Use this webpage to perform a virtual titration.

Practice Problems:
calculate the unknown quantity for the complete neutralization of the following.
Inclass Assignment 244:
This assignment must be turned in by the end of class tomorrow to receive credit.
Scoring criteriaWork these titration calculations:
 A titration of 15.0 cm^{3} of household ammonia, NH_{3}, required 38.57 cm^{3} of 0.78M HCl. Calculate the molarity of the ammonia.
 What volume of 0.5M HNO_{3} is required to neutralize 25 cm^{3} of a 0.2M NaOH solution?
 Calculate the volume of 0.6M HNO_{3} necessary to neutralize 28.55 cm^{3} of 0.45M KOH.
Research Links:
Answers to titration problems: