Special symbols
Important: I'm not great with special symbols, so I would additionally appreciate additions and corrections.
Typst has a great support of unicode. That also means it supports special symbols. They may be very useful for typesetting.
In most cases, you shouldn't use these symbols directly often. If possible, use them with show rules (for example, replace all -th with \u{2011}th, a non-breaking hyphen).
Non-breaking symbols
Non-breaking symbols can make sure the word/phrase will not be separated. Typst will try to put them as a whole.
Non-breaking space
Important: As it is spacing symbols, copy-pasting it will not help. Typst will see it as just a usual spacing symbol you used for your source code to look nicer in your editor. Again, it will interpret it as a basic space.
This is a symbol you should't use often (use Typst boxes instead), but it is a good demonstration of how non-breaking symbol work:
#set page(width: 9em)
// Cruel and world are separated.
// Imagine this is a phrase that can't be split, what to do then?
Hello cruel world
// Let's connect them with a special space!
// No usual spacing is allowed, so either use semicolumn...
Hello cruel#sym.space.nobreak;world
// ...parentheses...
Hello cruel#(sym.space.nobreak)world
// ...or unicode code
Hello cruel\u{00a0}world
// Well, to achieve the same effect I recommend using box:
Hello #box[cruel world]
Non-breaking hyphen
#set page(width: 8em)
This is an $i$-th element.
This is an $i$\u{2011}th element.
// the best way would be
#show "-th": "\u{2011}th"
This is an $i$-th element.
Connectors and separators
World joiner
Initially, world joiner indicates that no line break should occur at this position. It is also a zero-width symbol (invisible), so it can be used as a space removing thing:
#set page(width: 9em)
#set text(hyphenate: true)
Thisisawordthathastobreak
// Be careful, there is no line break at all now!
Thisi#sym.wj;sawordthathastobreak
// code from `physica` package
// word joiner here is used to avoid extra spacing
#let just-hbar = move(dy: -0.08em, strike(offset: -0.55em, extent: -0.05em, sym.planck))
#let hbar = (sym.wj, just-hbar, sym.wj).join()
$ a #just-hbar b, a hbar b$
Zero width space
Similar to word-joiner, but this is a space. It doesn't prevent word break. On the contrary, it breaks it without any hyphen at all!
#set page(width: 9em)
#set text(hyphenate: true)
// There is a space inside!
Thisisa#sym.zws;word
// Be careful, there is no hyphen at all now!
Thisisawo#sym.zws;rdthathastobreak