In North America they are, however, required, and we too must follow local rules. One quite common rationale says that you cite sources to establish that your work is your own, that you are not plagiarizing. I do not myself see the force of that. No, technicalities do not keep people honest. Please cite your sources for more positive reasons.
Footnotes trace a kind of paper trail for future hunters to follow.
Hopefully those who follow will feel that our work is solid enough for them to build on to it, for that is how knowledge advances. You will also be so pleased when it sounds good, euphonious, persuasive, clear. Get someone else to read it. Please, please proof your work carefully. Check your spelling.