All caps are typically used for either of two reasons: Visual Style Capital letters are often used on covers of magazines, in logos and artsy-typography, usually to emphasise the visual style of the letters themselves, rather than the word.
( Example Image )
Contextual emphasis: Capital letters can be considered a third form of emphasis, among Italics and Bold text.
They are used to denote a louder, almost shouting (and in many cases actually shouting) pronunciation.
This is done by tabloid newspapers, for example:
Political Correctness Gone MAD!
(in this example, the exclamation mark is used, erroneously, to add even more volume)
Legal documents sometimes use capital letters to denote areas of special importance.
They are, presumably, trying to avoid the area being overlooked by the reader, by making it stand out from the rest of the text.
This product comes with NO WARRANTY.
There are also technical reasons for using capital letters.
Here are just some examples of this: Typesetting systems (old computers, stencils, ...) that don't allow for italics or bold text may encourage some to use capital letters instead Capital letters to denote a SURNAME as opposed to a first name (according to wikipedia, this is done in francophone countries)
There are suggestions, some call it a consensus, that upper case text is harder to read than correctly capitalised text.
This, to my knowledge, first manifested itself in public policy when British road signs were changed in 1957.
The Worboys Committee proposed a new type face called Transport , using lower case letters for the first time.
This is based on the idea that one reads the shape of the word rather than each individual letter.
The All caps article on Wikipedia summarises the evidence for this.
It's not even always a good idea to capitalise acronyms and initialisms, as illustrated by this ridiculous example: Have they turned on the LASER yet?
Rhodri rightly says that this is uncommon and only happens to de-facto words.
As Jimi pointed out, ALL CAPS in email and instant messaging conversations is considered shouting, and people who use it extensively are considered trolls .
english.stackexchange.com/users/691/Stefano Palazzo
ALL CAPS ON THE INTERNET OR IN WRITTEN ELECTRONIC DOCUMENTS
IS OFTEN THE RESULT OF A MISTAKE BY OLDER, OR LESS EXPERIENCED, COMPUTER USERS
WHO USE CAPSLOCK AND FORGET
THAT IT IS ENABLED.
GENERALLY, WHEN IT IS NOT A MISTAKE, IT DENOTES SHOUTING, EMPHASIS, IMPORTANCE, OR URGENCY.
IT CAN ALSO BE USED IN SCENARIOS
WHERE CLEAR TEXT IS
REQUIRED - THOUGH
THIS IS USUALLY EMPLOYED WHEN WRITING BY HAND.
MY ANSWER IS IN ALL CAPS
BECAUSE IF YOU READ IT BACK IN YOUR HEAD
IT WILL SOUND LIKE I'M SCREAMING
AT
YOU MARCO :D!
english.stackexchange.com/users/3576/RolandiXor
They are usually used to add emphasis.
They are also often used in place of italics in situations where those can't be displayed.
english.stackexchange.com/users/None/
All caps is used primarily for emphasis.
When used excessively in an electronic message (email, discussion thread, etc), this is called shouting and it is considered quite rude.
For more on the various uses of all caps , see the Wikipedia article .
english.stackexchange.com/users/2705/Jimi Oke
Lo, these many years ago, I took a typing class (manual typewriters, for a true sense of age!).
We were instructed to use ALL CAPS as a substitute for bold and underline ( _ _) as a substitute for italics .
When I started going on line (long before publicly available Internet), I was taught to surround text with asterisk (*) when I intended bold and with underscore (_)
when I intended italic .
If you pay attention to the markup used in this forum, you can see how those conventions have been honoured and expressed over time and through changing technology.
In English classes (native English, not ESL or second-language) we were also taught to use ALL CAPS to separate the 'description' from the 'real' text.
So, in your error message example, ERROR: is telling you that what follows is an error message as distinct from a warning message (WARNING:) or a purely informational message (INFO:).
A similar concept applies to dialogue the way it is normally written in plays.
As a side note, I was also taught that underline was introduced with the typewriter and that previous to that scribes and typesetters used actual italics (and bold).
I have not been able to confirm that anywhere, though.
The other answers are, of course, also correct.
english.stackexchange.com/users/3582/Ron Porter
Used to emphasize a point you want to make.
But using it excessively would seem like you are shouting at the top of your voice.. which is not very nice.....
All CAPITALS make reading quite difficult too...
english.stackexchange.com/users/3584/Dharu Krish
In some usage circles, titles and other things that would properly be set in italic are translated to uppercase instead.
For example: The Soandso Players will be performing THE TURN OF THE SCREW at the K---- Memorial Theater this August 30 th and 31 st .
I am told that this is a carryover from typewritten manuscripts, particularly stage plays and the like, where upper case is used to distinguish character names from dialogue.
english.stackexchange.com/users/1475/zwol
In many error messages and conversations, I come across words in all capital letters, as demonstrated in the examples below.   ERROR: Please type your e-mail address.   or   ME: I can't make it   SHE: I HATE you.   ME: I'm soo sorry.   What is the typical meaning of or reason for these words written in all capital letters?
What do all capital letters typically refer to in writing?
english.stackexchange.com
<meaning><writing><capitalization>
english.stackexchange.com/questions/8672
english.stackexchange.com/users/3574/Marco Ceppi
There are many different reasons for using all caps. One example is for visual style, such as magazine covers, and another might be for contextual emphasis. Capital letters are sometimes used to denote areas of special importance, particularly in legal documents. However, when use in an e-mail or message conversation, ALL CAPS is considered shouting and it is considered quite rude. All caps is used for visual or linguistic effect, to create emphasis. In legal documents it can be used to focus on some text. When it first appeared on roadsigns in the UK, it was believed it was easier to use. It is not recommended capitalising acronyms, whereas all capital letters is considered shouting in modern forms of communication. It is also use in some circles to replace Italics, as in the theatre industry. It can also be used to separate a description from a real text.
There are many different reasons for using all caps. One example is for visual style, such as magazine covers, and another might be for contextual emphasis. Capital letters are sometimes used to denote areas of special importance, particularly in legal documents. However, when use in an e-mail or message conversation, ALL CAPS is considered shouting and it is considered quite rude. Sentences may be written in all capitals for emphasis but when used too much it is rude, like raising your voice.
Legal documents sometimes use capital letters to denote areas of special importance. Capitals can also be used to add emphasis, as an alternative to italics or bold type. However, when used expensively in electronic messages, it is considered to be shouting and rude. There are a few reasons why words might be written in all capitals. Mainly, this is done to add emphasis to a word or phrases. Additionally, in some circumstances it may be used when italics are not possible. Extensive use of all-capitals is considered shouting.
This product comes with NO WARRANTY. It's not even always a good idea to capitalise acronyms and initialisms, as illustrated by this ridiculous example: Have they turned on the LASER yet?
This product comes with NO WARRANTY. It's not even always a good idea to capitalise acronyms and initialisms, as illustrated by this ridiculous example: Have they turned on the LASER yet?
Used visually or for linguistic emphasis Used in legal documents. To focus on the text. Technical reasons for use of caps. Its first appearance. Not recommended capitalising acronyms. In modern forms of communication, all caps can be considered as shouting. used to separate description from real text. It can make reading difficult In some cirlces, titles usually set in Italics are converted into uppercase.
Sentences may be written in all capitals for emphasis. Text in all capitals is often seen as shouting.
Writing whole words in all capital letters is normally done to add emphasis. If used extensively, all-capital letters can denote louder pronunciation or shouting. In some circumstances, all-capitals may be used where italics are not available.