Here are brief notes on the punctuation mark full stop with one example in each sentence:
The full stop, also known as a period, denotes the end of a sentence. Despite the rain and wind, we decided to go for a hike.
It goes at the end of declarative, imperative and exclamatory sentences. I need to finish this report by 5pm!
The full stop is usually followed by a single space. The movie was fantastic!.
In abbreviations, the full stop is used with no space after it. e.g. i.e. Mr. Dr.
In numbers where the digits represent whole numbers, periods are used to group them. 1,234.56.