Each person is incomparable of the others and exist personal qualities, that prove therefore it. Thanks to sciences we know that to each human being account with physiological and behavioural qualities, that cause that each person is unique. Between these qualities they are possible to be mentioned the conformation of the face, the fingerprints, the ocular landlords, the voice, the company/signature, the way to walk and the form to key. The biometry is the science that is in charge of the study and the measurement of all these qualities. This science has been present for many years. The qualities analyzed by the biometry denominate biometric indicators and must fulfill certain parameters, so that they can be used in a biometric analysis.

These parameters are only four: cuantificabilidad, permanence, unicity and universality. The cuantificabilidad means that a biometric indicator must be able to be measured in quantitative form. Taking the example from the fingerprints, these can be quantified when studying and to detail to their components like crests and valleys. The permanence means that a biometric indicator must be always present in a person and not to disappear over the years. In this case it is possible to be something flexible, because of accidents or biometric diseases some maracas can disappear. For example, a person who loses her hands will not be able to have fingerprints. The unicity refriere to that a biometric indicator must have a unique disposition in each person. The fingerprints, the ocular landlords and other biometric qualities, are unique in each human being and not even they are identical in the binoculars.

Universality means that a biometric indicator must be present in all the human beings. As with the permanence, some exceptions exist. At the time of going to the biometric systems, it is necessary to have present the parameters previously mentioned, to make the best election. We think that we managed a company of construction and that we needed to implement an access control, biometric, so that only our workers enter to one it builds. It is not a secret that the hands of the workers of the construction always are going to be in contact with the enemy with dirt and other substances, reason why to use a reader of tracks would not be most intelligent.