What fbclid actually is
fbclid stands for Facebook Click Identifier. Meta appends it automatically the moment you tap an outbound link inside Facebook or Instagram, so you never see it on a link someone typed by hand. It is not a campaign label like the utm_ family: it is generated per click, and its job is to let the destination site tell Meta "the person who arrived with this exact value went on to buy something", which is how conversion reporting and the Conversions API line up ad spend with outcomes.
That per-click nature is the important part. Two people tapping the same post get different fbclid values, which is why it belongs in the identifier family rather than the labelling family.
Is it safe to remove?
For you as the visitor, yes. The page loads identically without it; nothing about the destination depends on the value. What breaks is measurement on the advertiser's side, since stripping it means their conversion cannot be matched back to the ad you clicked. If you are sharing a link with a friend, removing it is the polite move because you are otherwise passing along an identifier tied to your click. If you are the advertiser, leave it alone.
Does it survive a redirect?
Sometimes, and that is exactly where attribution quietly dies. Many redirect services and link shorteners drop unrecognised query parameters when they forward the visitor, so a chain that passes through one of them can arrive at the landing page with fbclid missing. If your Meta conversions look lower than your own analytics suggest, a hop that eats parameters is one of the first things worth checking.
Why you are seeing it
Usually because you copied a link out of the Facebook or Instagram app to share or bookmark it, and the app's version of the URL already had the click ID welded on. It is harmless to keep, slightly leaky to share, and trivial to strip with the decoder above.