What gclid actually is
gclid is the Google Click Identifier. When auto-tagging is switched on in a Google Ads account, Google appends it to the landing page URL on every ad click. Nobody types it, and you cannot meaningfully choose its value. It exists so that conversions recorded on the site can be joined back to the specific click, and therefore to the campaign, ad group, keyword and device behind it, without the advertiser having to hand-build UTM parameters for all of that.
This is why a Google Ads account can report keyword-level conversion data while the URL only carries one opaque parameter: the detail lives in Google's records, and gclid is the key that unlocks it.
gclid, wbraid and gbraid
You may see two relatives. wbraid and gbraid appeared as privacy-scoped alternatives for traffic involving iOS, where per-user identifiers became restricted. The practical difference is that they are designed to support aggregated measurement rather than pinpointing an individual click. If you see wbraid or gbraid instead of gclid, nothing is broken; you are looking at the privacy-preserving path.
Is it safe to remove?
For a visitor, yes, the page is identical without it. For the advertiser it is load-bearing: strip gclid and the conversion that follows cannot be attributed, so the campaign looks worse than it performed. The common self-inflicted version of this is a redirect or a canonical setup that quietly discards query parameters between the ad click and the page that fires the conversion tag.
A caution about sharing
Because gclid is per click, a URL you copied off a landing page after clicking an ad carries a token tied to your visit. Sending it to someone else does not harm you, but it does pollute the advertiser's data with a click that never happened. Use the cleaned link from the decoder above.