"Recognition of some words is naturally hindered by the presence of two special characters, þ, called "thorn," and ð, called "edh," which served in Old English to represent the sounds now spelled with th."


Note that there was never any distinction made between the two th sounds that English presently carries in that both were represented by either the ð or the þ. (One can feel the difference by putting the hand about a half inch from the mouth then saying the words thin and there.)