There have been many theories launched over who created the runes. Some of these theories have more supporters than others, but they all have one thing in common. None these theories can be proved 100%. No runic inscriptions, as we know the runes, can be dated with certainty to before 200 AD.
I choose to follow the theory that runes were created about 100 - 200 AD among the Goths or other Germanic tribes located in an area north of the Black Sea. The runes may have been inspired by the Greek and Latin alphabets. There are many arguments for this theory. Later on the runes were spread all over middle and northern Europe by the migration of these tribes.
The runes were used by the Goths, the Herulers, the Germans and the Frisisans in south and middle Europe and the Angles and Saxons in the west. In the north they were used by the Norwegian, Swedish and Danish people, their counterparts in Iceland and Greenland and the Sami of Lapland ( northwest Russia and northern Sweden, Norway, and Finland) as well.
By 300 AD the runic alphabet was the only alphabet used in Scandinavia. However, it went out of use in middle Europe due to the popularity of the Latin alphabet, which had followed the expansion of Christianity.
The runes could be written from left to right or right to left. They also could be written with the first sentence proceeding right to left and the second sentence proceeding left to right (boustphedon). Additionally, runes were sometimes written as a mirror image ("venderuner"), upside down ("stupruner") or bound together ("bindrunes") like the Norwegian Æ (A+E). A single rune could also signify two runes. For example, the rune "FE" could signify "FE + FE".
The runes were often written as a continuous link of text, without spaces between the words or sentences. If the rune master wanted to separate words or sentences from each other, he used notation similiar to the letter X, or perhaps one, two or three points placed one over the other. For example, if he used two points in this manner he might write: "I:MAKE:SPACE:WITH:TWO:POINTS".
There are no lowercase runes, only uppercase runes.
There were no limits to the format the runes were written in. The runes could be written in all kinds of directions and upon almost any kind of common material - as beautiful decorations or as a hidden, magic formula. When runes were carved in stone, the runes were created by carving many points close to each other, until the rune master had a complete line.
FOUR OTHER THEORIES ABOUT THE HISTORY OF THE RUNES
1) The runes were introduced to Scandinavia during the same period that the well known spiral-ornaments were introduced from Crete - about 1800-400 BC. According to this theory, the Goths were already familiar with the art of runes before they left Scandinavia between 200 BC and 200 AD. However, this theory is not so widespread.
2) Kjell Aartun is a doctor of philosophy and and language-researcher who writes in his book, (RUNER i kulturhistorisk sammenheng, En fruktbarhetskultisk tradisjon, Pax Forlag, Oslo 1994.), that he has proven that the runes were not inspired by the Greek and Latin alphabets. He argues that it is opposite, maintaining that the Norwegian runes are identical with runes which were used in Semitic language areas such as Trojan Asia Minor and Canaan (Palestine) as far back in history as 2000 BC.
The runes are, after Kjell Aartun’s opinion, one of many oriental writing-systems which were the basic platform by which the Greek and Latin alphabets later developed. Additionally, he writes that he can prove that the first Norwegian runic inscriptions were written in a Semitic language, citing known cult-based erotic texts, many of which included holy depictions of the act of making love.
According to Aartun, new archeological finds show that many people from the Mediterranean Sea area, and especially the Cretans (who were Semitic), often traveled to the north on trading tours. He says that during the Migration Period many Semitic-speaking people came to Norway. Aartun writes that this conclusion is born out by actual facts which Snorri refers to when saying: "these Asians was called aeser(...) in the northern countries the Asians spread so much that their language was the common language in all these countries."
Kjell Aartun's theories are not accepted by authoritive Norwegian rune-ologists. However his theory has supporters as for example on this Internet site about Blekinge's Most Ancient Runic Inscriptions
3) TURGAY KÜRÜM of Turkey writes on his web-page that the purpose of his article is to draw the readers' attention to the fact that the Futhark alphabet is of the very same origin as the ancient Turkish inscriptions of the Gokturk alphabet.
4) The runes created in South-Scandinavia in the 300's AD were inspired by the Latin alphabet, but put in a Scandinavian cultural relation. South-Scandinavia was a center of runes in ancient times.