An abbreviation is a shortened form of a word, e.g. Mr for Mister. An acronym is a form of abbreviation which is usually produced from the initial letters of words e.g. lidar from light detection and ranging. An abbreviation also has to be distinguished from a symbol e.g. using + for plus and from contractions where letters are omitted e.g. fo'csle.
Only use an abbreviation or acronym if it is used more than twice in the text. Spell out the abbreviation or acronym the first time it is used and follow it by the shortenned form in parentheses. Do this both in the text and in the abstract. So
The full point is usually used after abbreviations but not for:
The abbreviations 'e.g.' and 'i.e.' are never followed by a comma.
An acronym is an abbreviation formed from letters in a phrase. The two principal forms of acronym are:
NATO, North Atlantic Treaty Organization
At some point this type of acronym metamorphoses into a standard word (e.g. radar) and no longer needs defining.
G.B.
However this rule is not strictly adhered to so we have
WMO, World Meteorological Organization
Do not back-capitalise abbreviated phrases to suit an acronym's capitaliation. So