A full stop can be used on different occasions, such as:

A full stop is used at the end of a complete sentence with a complete meaning. Remember, the full stop is necessary at the end of a sentence to let the reader know that the sentence has finished. Check out the examples:

Some sentences are not actually real sentences because they do not have subjects or verbs, but they convey a complete meaning. These sentences are called fragment sentences and we must use a full stop at the end of them.

Full stops can be used in abbreviations to indicate the omission of letters. When abbreviating a phrase that consists of multiple words, we typically use a letter to represent each word and separate them with a full stop. Here are a few examples:

When we use honorific titles in written form to address or refer to somebody, we usually use a period after them (in American English). Here are the examples:

We use "AM/PM" to indicate the time. In British English, we write them using lowercase letters and with full stops:

In American English AM/PM are usually written in uppercase letters and without full stops:

Both forms are correct and their usage depends on the variety of English you are using.

We can use full stop as a decimal point in numbers:

We also use full stops when writing website addresses, versions of software, IP addresses, and format of files. For example:

Do not confuse abbreviations with acronyms. We do not use full stops with acronyms and initials. For example:

When reporting direct speech, the period is put inside the quotation marks. Check out the example:

Also, pay attention to the following examples:

When an abbreviation has a period in the end and it is also used at the end of the sentence, then you should use only one full stop at the end of the sentence. for example:

The first letter after a period has to be capitalized. Here is an example:

There is no space before the full stop and one space after it.