Wikipedia: The period symbol derives from Aristophanes of Byzantium who invented the system of punctuation where the height of placement of a dot on the line determined its meaning. The high dot (.) was called a "periodos" and indicated a finished thought or sentence, the middle dot (·) was called a "kolon" and indicated part of a complete thought, while the low dot (.) was called a "komma" and also indicated part of a complete thought.
This morning I was wondering about period ( . ) after a sentence.
I am not very familiar with a Grammar rule about the same and would like to listen from you.
Common sense often does not stand up to the conventions of Grammar. I am still speculating thusly:
The period or full stop is put after a group of words which are not abbreviations to indicate that those words together make a part of a completed thought which is distinct from other parts.
In other words: A period is a punctuation mark, used to create a boundary where a sentence is separated from any other.
[ Well, this might be the most vulnerable part of my speculation from the viewpoint of English Grammar! Because a sentence in isolation might not be a sentence without a period.]
In that case, the significance of a period after what we call a sentence is only when there must be at least one other sentence following it or in other words, every last sentence of any writing can be left without a period.
I hope that any objection to speculation above comes with the suggestion that a sentence without an end in question mark, exclamation or with any special punctuation, must end in a period.
Here we have a definition of 'Sentences' from Wikipedia:
In the field of linguistics, a sentence is an expression in natural language. It is often defined as a grammatical unit consisting of one or more words that bear minimal syntactic relation to the words that precede or follow it. A sentence can include words grouped meaningfully to express a statement, question, exclamation, request, command or suggestion.
A sentence can also be defined in orthographic terms alone, i.e. as simply that which is contained between a capital letter and a full stop. This is arguably more accurate than definitions which conflate orthography and grammar, given the variety of structures which are possible between the capital letter and a full stop. For instance, the opening of Charles Dickens' well known novel, Bleak House, begins with the following three sentences:
London. Michaelmas term lately over, and the Lord Chancellor sitting in Lincoln's Inn Hall. Implacable November weather.
The first sentence involves one single word, a proper noun. The second sentence has only a non-finite verb. The third is a single nominal group. Only an orthographic definition can hope to encompass this variation.
Now, if instead of writing the entire passage as Dickens does above, if a writer chooses to write just one word without a period:
Will that be considered a sentence? No, I guess because it doesn't have a period.
What about the second sentence in the passage without a period:
Michaelmas term lately over, and the Lord Chancellor sitting in Lincoln's Inn Hall
Does this qualify as a sentence?
It might make for interesting discussion.