From https://www.gnu.org/software/grep/manual/grep.html#The-Backslash-Character-a... :
The ‘\’ character, when followed by certain ordinary characters, takes a special meaning:
...
‘<’
Match the empty string at the beginning of word.
‘>’
Match the empty string at the end of word.
I'd be happy to use any other (more readable!) whole-word matching grep trick, this <one> just happens to be committed to my cmdline muscle memory.
There is 'grep -w' which I use for this.
Miroslav