In abbreviations made up of the initial letters of a number of words the usual modern practice is to omit full stops: BBC, UN, USA. In British, but not in American English, it is also becoming increasingly common to omit the full stop after an abbreviation containing the first and last letters of a word (Dr, Ltd, St)

Practice differs greatly with regard to the use of full stops in abbreviations: the general trend, however, is to use full stops less and less. In abbreviations made up of the initial letters of a number of words the usual modern practice is to omit them: BBC, UN, USA. It is not incorrect to write B.B.C. etc., but it is not necessary to do so. In an acronym, a string of initial letters that is pronounced as a word (BUPA, NATO, Aids), the use of full stops is even less necessary. In British English, it is becoming increasingly common to omit the full stop after an abbreviation containing the first and last letters of a word (Dr, Ltd, St). In American English, however, the full stops after such abbreviations are more likely to be retained