Are there any invisible characters? I have checked Google for invisible characters and ended up with many answers but I'm not sure about those. Can someone on Stack Overflow tell me more about this?
Also I have checked a profile on Facebook and found that the user didn't have any name to his profile? How can this be possible? Is it some database issue? Hacking or something?
When I searched over Internet, I found that 200D is an ASCII value with an invisible character. Is it true?
I just went through the character map to get these. They are all in Calibri.
Number Name HTML Code Appearance ------ -------------------- --------- ---------- U+2000 En Quad   " " U+2001 Em Quad   " " U+2002 En Space   " " U+2003 Em Space   " " U+2004 Three-Per-Em Space   " " U+2005 Four-Per-Em Space   " " U+2006 Six-Per-Em Space   " " U+2007 Figure Space   " " U+2008 Punctuation Space   " " U+2009 Thin Space   " " U+200A Hair Space   " " U+200B Zero-Width Space ​ "" U+200C Zero Width Non-Joiner ‌ "" U+200D Zero Width Joiner ‍ "" U+200E Left-To-Right Mark ‎ "" U+200F Right-To-Left Mark ‏ "" U+202F Narrow No-Break Space   " "
How a character is represented is up to the renderer, but the server may also strip out certain characters before sending the document.
You can also have untitled YouTube videos like https://www.youtube.com/watch?v=dmBvw8uPbrA by using the Unicode character ZERO WIDTH NON-JOINER (U+200C), or ‌ in HTML. The code block below should contain that character:
There is actually a truly invisible character: U+FEFF.
This character is called the Byte Order Mark and is related to the Unicode 8 system. It is a really confusing concept that can be explained HERE The Byte Order Mark or BOM for short is an invisible character that doesn't take up any space. You can copy the character bellow between the > and <.
Here is the character:
> <
How to catch this character in action:
> and <,You will notice that when your caret gets to the place you pasted the character, it will briefly stop for around half a second. This is becuase the caret is passing over the invisible character. Even though you can't see it doesn't mean it isn't there. The caret still sees that there is a character in that area that you pasted the BOM and will pass through it. Since the BOM is invisble, the caret will look like it has paused for a brief moment. You can past the BOM multiple times in an area and redo the steps above to really show the affect. Good luck!
EDIT: Sadly, Stackoverflow doesn't like the character. Here is an example from w3.org: https://www.w3.org/International/questions/examples/phpbomtest.php
Other answers are correct - whether a character is invisible or not depends on what font you use. This seems to be a pretty good list to me of characters that are truly invisible (not even space). It contains some chars that the other lists are missing.
'\u2060', // Word Joiner
'\u2061', // FUNCTION APPLICATION
'\u2062', // INVISIBLE TIMES
'\u2063', // INVISIBLE SEPARATOR
'\u2064', // INVISIBLE PLUS
'\u2066', // LEFT - TO - RIGHT ISOLATE
'\u2067', // RIGHT - TO - LEFT ISOLATE
'\u2068', // FIRST STRONG ISOLATE
'\u2069', // POP DIRECTIONAL ISOLATE
'\u206A', // INHIBIT SYMMETRIC SWAPPING
'\u206B', // ACTIVATE SYMMETRIC SWAPPING
'\u206C', // INHIBIT ARABIC FORM SHAPING
'\u206D', // ACTIVATE ARABIC FORM SHAPING
'\u206E', // NATIONAL DIGIT SHAPES
'\u206F', // NOMINAL DIGIT SHAPES
'\u200B', // Zero-Width Space
'\u200C', // Zero Width Non-Joiner
'\u200D', // Zero Width Joiner
'\u200E', // Left-To-Right Mark
'\u200F', // Right-To-Left Mark
'\u061C', // Arabic Letter Mark
'\uFEFF', // Byte Order Mark
'\u180E', // Mongolian Vowel Separator
'\u00AD' // soft-hyphen
The question about invisible characters in Unicode deserves a more thorough explanation.
Here are 134 invisible characters →← and here is their escaped ASCII representation: U+00AD U+061C U+180E U+200B U+200C U+200D U+200E U+200F U+202A U+202B U+202C U+202D U+202E U+2060 U+2061 U+2062 U+2063 U+2064 U+2067 U+2066 U+2068 U+2069 U+206A U+206B U+206C U+206D U+206E U+206F U+FEFF U+1D173 U+1D174 U+1D175 U+1D176 U+1D177 U+1D178 U+1D179 U+1D17A U+E0001 U+E0020 U+E0021 U+E0022 U+E0023 U+E0024 U+E0025 U+E0026 U+E0027 U+E0028 U+E0029 U+E002A U+E002B U+E002C U+E002D U+E002E U+E002F U+E0030 U+E0031 U+E0032 U+E0033 U+E0034 U+E0035 U+E0036 U+E0037 U+E0038 U+E0039 U+E003A U+E003B U+E003C U+E003D U+E003E U+E003F U+E0040 U+E0041 U+E0042 U+E0043 U+E0044 U+E0045 U+E0046 U+E0047 U+E0048 U+E0049 U+E004A U+E004B U+E004C U+E004D U+E004E U+E004F U+E0050 U+E0051 U+E0052 U+E0053 U+E0054 U+E0055 U+E0056 U+E0057 U+E0058 U+E0059 U+E005A U+E005B U+E005C U+E005D U+E005E U+E005F U+E0060 U+E0061 U+E0062 U+E0063 U+E0064 U+E0065 U+E0066 U+E0067 U+E0068 U+E0069 U+E006A U+E006B U+E006C U+E006D U+E006E U+E006F U+E0070 U+E0071 U+E0072 U+E0073 U+E0074 U+E0075 U+E0076 U+E0077 U+E0078 U+E0079 U+E007A U+E007B U+E007C U+E007D U+E007E U+E007F
Are there more? Yes.
Are there invisible characters in the ASCII range? Depends on the font.
The Unicode Standard enables anyone to read and write in their own language. To do that, it lists unique code points (U+hex), that are categorized into letters (D,ž,Dž,ʶ,愛,), symbols (+∊≠,£¥₪,҂˚˟˿), marks (ם֑֟֯ ,ী,◌҉ ), separators ( , , , , ), emojis (,,), and much more. ASCII/Basic Latin is the very beginning of the table and more code points are added every update.
Simply listing unique numbers for characters is not enough. Characters can change their shape or change the sentence depending on the context. To support that, every code point comes with a list of properties . These properties may define the width (AＡ), its role in the sentence (-“.), its direction (cכ), and much more.
Most invisible characters have the property General_Category=Format (other answers here included Spaces as well). Theis characters have a supporting role to a word/sentence. Here are some examples:
This all leads to talk about exploiting invisible characters for homograph attack/visual spoofing. Sometimes it's harmless like invisible names and titles but in lots of cases they are used maliciously. For example U+202E is one invisible character that keeps doing more harm than good for decades!!
Last point, there is another way to make invisible characters using fonts. Fonts are files that store glyphs (pictures of characters), that present the characters' look. If the font does not contain a glyph for a codepoint, a substitute/replacement character is displayed (e.g. �, □). But if the font contains a transparent glyph for a codepoint, then the character is invisible, only when displayed by that font. This is the only way to have invisible characters in the ASCII range (for example can you see →``← U+000C Form Feed).
Hope you find this explanation helpful and may you check strings for invisible characters more often
Yes you can use invisible or blank name on facebook by using some HTML code/symbols.
Method 1:
Copy and paste (ﹺ ﹺ) symbols without brackets in your first and last name field.
Method 2:
Click on edit name. Now copy and paste following symbol in first and last name.
ՙՙ ՙՙ
An invisible Character is , or U+200b
