Some Rune sets, and some websites, include a “Blank Rune”, giving them 25 elements to use. ( I can’t call them letters, because, an empty space isn’t a letter).
There is a debate, at times fierce and aggressive, about whether those who use the blank rune are new-age vandals abusing an ancient and honorable system; or heroic adventurers breaking new ground for our modern age.
The Blank Rune (also called “Odin Rune”, or “Wyrd Rune”) appears to be a creation of Ralph Blum for his book “The Book of Runes: A Handbook for the Use of an Ancient Oracle” , first published in 1982. There is even a suggestion that he created it because printing the tiles was more efficient on a 5 X 5 grid than a 5 x 4 grid.
Interestingly enough, when the Runic alphabet was used by our forerunners, the writers used a : to separate the words, not a “space”, which seems to imply that they had no need for a blank.
My own belief is that this “Blank Rune” is a modern “fix” that misunderstands the original purpose of the Runic alphabet, which was not just a set of individual “symbols”, but a system for writing. More importantly, the power in the Runes is in their meaning as objects or concepts. That power can be amplified in a bind rune or a runic phrase. This obviously isn’t possible with a “blank”.
Also, I would caution against attempting to use a “Blank” for magic; as there is no focus, just an absence, which can provide a doorway for unwanted “elements”.
And in answer to those who interpret the blank rune as Odin, or “Fate (or Wyrd)", I would say that Odin already has his own Rune: “Ansuz”, while the Wyrd, in my mind, is implied in “Perthro”.
BUT; it’s still useful to have a “Blank”…in case you lose one of the 24 “Real” Runes :-P
Futhark is to runes what Alphabet is to our Roman lettering, where “Alpha” is A, and “Bet” is B. With the Futhark, however, we have the initial sounds of the first six runes; Fehu, Uruz, THurisaz, Ansuz, Raido, Kenaz.
Just how old the lettering system is, or where it came from, no one really knows. However, something that I do find intriguing is that none of the “shapes” use a cut from left to right; only up and down or diagonal. For me, this seems to indicate that during the period when the runes were being “codified”, they were being inscribed on strips of wood; possibly on branches that have been split open along their length. You will see that if you cut along the grain, the cut will seal up and the groove will disappear. If you cut across the grain, then the groove will remain, and then it can be coloured.
Finally, We call this the “Elder” Futhark to distinguish this set from later (9th Cent) Younger Futhark of 16 runes, and the Anglo Saxon and Northumbrian Futharks each of 33 runes. Nowadays, the Elder Futhark is the one used most frequently for rune casting and other magical purposes.