Correlate breadcrumbs front end with backend?

I’ve only been reading about sentry. The most interesting feature for me is the breadcrumbs. I’d really like to visualise what’s going on in my application and breadcrumbs seems to be great for this. I’ve had a brief look at the docs and I would like to know how breadcrumbs from front end are correlated with corresponding breadcrumbs in the backend. I was expecting to see some kind of correlation id. How does this work? Thanks!