Hello, I have recently begun to learn Icelandic. I have noticed that the words "síðan" and "þá" can both be used to mean "then", but I'm not sure what the difference is. I know that "síðan" also means "since" and that "þá" is also a pronoun. My best guess is that one is used in the past tense and one is used in the present. My second-best guess is that the words are interchangeable. I would really appreciate an explanation of this, and an example of two sentences where the words would be used. Thank you!