Titrations involve using a burette to accurately measure the volume of one solution that is required to react completely with a known volume of a second solution (usually measured using a pipette). This then allows you to work out the concentration of the unknown solution.
You can find out more details about titrations here.
Titrations are usually carried out to determine the exact concentration of a solution but the same technique can sometimes be used for the preparation of soluble salts.
The most common titrations are those involving acids and alkalis but you may also come across: redox titrations ( such as iodometric titrations), complexometric titrations (such as those used for determining calcium) and precipitation reactions.
In general, an accurately measured amount of one reagent is placed in a flask or beaker below the burette and a suitable indicator added (if needed).
The second reagent, in the burette, is run into the one below by means of a tap until the indicator changes colour.
The volume of this second reagent is then read off the scale on the burette.
Given that you know the volumes of both solutions and the concentration of the titrant in the burette, you can then accurately work out the concentration of the solution in the flask that you are titrating against.