What are contextual alternates?

Contextual alternates are alternate characters included in some script typefaces to provide better joining behavior. For example, when using Caflisch Script Pro with contextual alternates enabled, the letter pair “bl” in the word “bloom” is joined so that it looks more like handwriting.


Image Source:
https://www.typenetwork.com/news/article/opentype-at-work-contextual-alternates

Source:
https://helpx.adobe.com/illustrator/using/arabic-hebrew.html