The word RUNE means secret or mystery. Runes had a religious meaning and were used in religious ceremonies. They were a charm or a spell as well as a way of writing messages.
The Anglo-Saxons believed that if you used the right runes in the right order, they could have magical powers. For example, a prisoner could magically release himself by carving certain runes

You can see that some of the runes are quite like capital letters:

Some are easier to guess if you turn them upside down,

although some are not at all what you might expect:

writan (= to carve runes) and ridan (= to interpret runes) became our words write and read.