# Similarity web interface instructions

Enter the terms or Concept Unique Identifiers (CUIs) whose similarity or relatedness you wish to compute into the fields labeled Term 1 and Term 2. You can enter any combination of terms or CUIs. For example:

1. heart attack and skull
2. C0018563 and C0037303
3. hand and C0037303

You can than either calculate the two terms similarity or relatedness. A discussion of the difference between similarity and relatedness is here.

To calculate the similarity you have two options:

1. SAB designates what UMLS source to obtain the hierarchical information
2. REL designates what relation information to use from the designated source

To calculate the relatedness you also have two options:

1. SABDEF designates what UMLS sources to obtain the definitions from
2. RELDEF designates what relations to use to create the extended definiton