 concept of availability in this module we will discuss about the valid name and available name first of all what is a valid name valid name we call it as which can be used or which is used which has acceptable name now when we are going to give a name to any species we have to take care of a few things first of all that name is available and second that name is valid if we talk about international code of zoological nomenclature in this article 8-20 this tells us that when we have to name a species we have to follow which rules an available name is not valid an available name can be valid or unvalid similarly an available name is not valid because if the name is not available how can we use it along with the criteria of availability it varies according to the nomenclature for this we use a term legitimate that when we are going to name any species for that it is necessary that some conditions which are international code for zoological nomenclature have been devised they should be fulfilled if that name is fulfilled on all those conditions then that name will be called an acceptable name otherwise that name is not acceptable now it is necessary to know what is the difference between a valid name and an available name first of all we see what is the meaning of an available name the meaning of an available name is that it is properly published now what is the meaning of an available name that while publishing a name it is necessary that the name which we are going to name should be its description its characters its details similarly what is the meaning of a valid name the meaning of a valid name is that this name is not pre-occupied that is this name is not used for any other taxa now if we talk about international code for zoological nomenclature then its article 11 through 19 i.e. from 11 to 19 the articles in these there are all pre-requisites for an available name and especially its article number 13a is very important now if we talk about article 13 then in article 13 this is mentioned that after 1930 whenever we are going to publish a name then with that name the name of the animal its description its characters its details and along with that the members of that species its comparison not only along with that comparison so that we can know the different members of that species how many character states are there or how many variability are there along with that we can also see that the closely related taxa along with that the character there are so many similarities differences are present this article 13 is related to all these things now whenever we are going to publish a name then it is important to follow article 13 i.e the name of that specimen its description now there are two things in it one is the name of the specimen its characters and the other its comparison now the description is very important i.e if we give the name of a specimen but we did not give the description of that specimen then this name will be called invalid name because this name its description is not worth any word it is technically rejected along with that the other important thing is that this specimen is compared to its characters so that we can see the comparison in its detail that the characters are closely related what are the differences what are the similarities so in this in this module we have seen that while keeping the name we have to strictly follow article 13a we have to give the description of the specimen if we do not give the description of the specimen then this name we will try