A zerowidthspace is a space that only serves to break up a word when formatting
Thisisanexampleofaverylongwordcreatedwithzerowidthspaces.Ifyouresizethewindow/rotateyourphonetoseehowitalwaysline-breaksonaword.
Thissimplyhasnospacesandasyoucanseeitistreatedasallonewordwhichjustkeepsgoingandgoingandgoing
If you're working on a website there's a good chance that someone will want to copy/paste it, automate using it, etc. Zero-width spaces will create no end of hassle to those people.