Use normally in sentences and paragraphs. Don't use them to end headers.

The exception to this is error messages, which should have a full stop at the end of the header. If there are two sentences to the error message, use to end the first sentence.

Where there is a sentence that ends with something in quote marks, the full stop should go "outside the quotation marks like this". It's the other way around for US English.

Don't use full stops:

• to end any text for radio buttons
• at the end of standalone links, for example, "Back"