Some of the teachings about the fundamental properties of the 22 Hebrew letters are that they:
^ Have fundamental intrinsic, spiritual and symbiotic meaning and that everything in creation is formed from them. We can think of them as the 22 letters of creation. This is similar to chemistry. For example, water is composed of the two elements: hydrogen and oxygen are formed into a molecule of water with two hydrogen atoms and one oxygen atom and where water's properties are derived from the arraignment of these three atoms of two different elements within the molecule of water. Likewise, the 22 Hebrew letters can be thought of similarly* as "letter elements" that then join together to form "molecule words" that have specific properties derived from the molecules words' elemental letters composition.
^ Have a number value and so too then do words. Further, these numeric values are an expression of the spiritual and symbolic meaning of the letters and words themselves.
^ Are made up of other letters. Again similar to how element atoms are made up of subatomic parts, i.e. protons, neutrons, electrons, etc. The exception to this is the letter י Yud. **
-------------------------
*Perhaps, coincidentally, water, mayim in Hebrew is spelled with three letters: Mem (מ )Yud (י) (Mem (ם).Two Mem (one is special way to write the letter when it occurs at the end of a word called a "final form" letter) and one Yud. So the familar H2O; hydrogen oxygen hydrogen is the same arrangement as Mem Yud Mem.
** ". . . a letter that is barely larger than a dot and cannot be divided into component parts. . . . "The Wisdom in the Hebrew Alphabet", p. 125; Rabbi Michael L. Munk , 1983 3rd ed. 2102 Mesorah Publications