An emoji is a code point, not an image. Every platform draws it from its own font, so the character you send and the character that arrives are the same number and different pictures — sometimes different enough to change the meaning of the message.
The clearest example is the pistol. Vendors redrew it as a water pistol between 2016 and 2018, one at a time, so for a period the same message read as a threat on one device and a joke on another.
What are the modifiers doing?
Adding information to the character before them. A skin tone modifier follows a base emoji and changes how it renders, which is why the sequence is two code points rather than one and why deleting it can take two presses.
The joiner does something similar at a larger scale. Several emoji joined by an invisible connector are displayed as one composite image where the platform has artwork for that combination — and as the separate components where it does not.
That fallback is why a family emoji sometimes arrives as several people in a row. Nothing is broken; the receiving platform simply has no single drawing for that sequence.
Why does the count come out wrong?
Because one visible emoji can be many code points. A composite sequence with a modifier can run to several, each of which costs four bytes in the usual encoding, so a short string of emoji consumes a surprising share of a character limit.
Deleting behaves accordingly. A single backspace may remove a modifier and leave the base emoji, or remove one component of a sequence and collapse the rest into something unintended.
The emoji byte article covers the storage side, and the practical consequence is unchanged: count after composing rather than before.
What is an invisible character for?
Occupying a field that requires content without displaying anything. A blank display name, an empty-looking message or a line with nothing on it are all done with a character that is real to the validator and invisible to the reader.
The characters used are borrowed rather than designed for it. A zero-width space is one option; a filler character from the Hangul block is another, and it works on platforms that reject the first because it is a proper letter with no visible form.
It is worth recognising because it is also used adversarially. Invisible characters inserted into text defeat exact matching and keyword filters, which is a reason to strip them from anything arriving from outside.
Where do kaomoji get their characters?
From wherever a shape was available. The faces built from punctuation draw on Japanese punctuation, Cyrillic and Greek letters, mathematical operators and box-drawing characters — chosen for how they look rather than what they mean.
That is why they survive copy and paste and why they occasionally render as boxes. A character borrowed from an uncommon block needs a font that covers it, and not every device has one.
They also predate emoji by a long way, which is the reason the convention reads horizontally in one tradition and vertically in another.
Which symbols are worth knowing?
The typographic ones a keyboard does not offer. The multiplication sign is not the letter x, the minus sign is not a hyphen, and the degree symbol is not a superscript o — and in each case the correct character sets properly and the substitute does not.
The dashes are the set most often confused. A hyphen joins words, an en dash spans a range, and an em dash breaks a sentence; using a hyphen for all three is common and reads as slightly wrong without anyone identifying why.
Copying them from a list is faster than remembering a keyboard shortcut, which is the entire reason these collections exist.
Do emoji sort or search sensibly?
Not really. They have no alphabetical position, so sorting places them wherever their code points fall, which groups them by when they were added rather than by what they show.
Search is worse. Matching an emoji requires the exact sequence including any modifiers, so a search for a base emoji misses every version of it carrying a skin tone — which is why filtering on emoji is unreliable in both directions.
For anything that has to be found later, the emoji is decoration and the searchable version belongs in words alongside it.
Questions people ask
Are new emoji safe to use? Give them a year. A recent addition renders as a box on any device that has not updated its font.
Do emoji have official names? Yes, and they are often narrower than the way the emoji gets used — which is part of why meanings drift.
Will my emoji look the same to everyone? No. Assume the artwork differs and avoid ones whose meaning depends on the drawing.
Do emoji work in a filename? Usually, and they cause trouble in scripts, archives and older systems. Not worth it.
Is an invisible character allowed in a username? Platforms differ, and several block it specifically.
Why do some emoji show as boxes? The device has no artwork for that code point, which happens with recent additions.
Copy the character rather than approximating it. Emoji copy and paste, symbols copy and paste and kaomoji cover the three collections, the invisible character tool provides the blank one, and the text repeater, text reverser, reverse words and shuffle words handle the transformations that go with them.