The 22 letters of the Hebrew alphabet divide into 5 phonetic groups, based on their origin in the mouth's vocal system:
Phonetically, any two letters of the same origin can be interchanged. Thus, there are many Hebrew words whose proximity in meaning stems from their phonetic equivalence.
These letter interchangings are often used in Kabbalistic analysis of Hebrew words of phrases, particularly from the Bible and the Talmud. These techniques are employed many times in different articles on this website, see for example here, and here.
To view a video discussing the origin of the throat and its relationship with the letters that emanate from it, see here.