Lead
minecraft:leadA lead is a utility item used to leash and lead mobs around the world. Once attached, a mob can be walked by holding the other end of the lead, or tied off to a fence post so it stays put. Leads can stretch up to 12 blocks (16 for a happy ghast) before snapping and dropping as an item.
FAQ
How do I craft a lead?
Combine 4 string with 1 slimeball in a crafting grid to make 2 leads.
What happens if I stretch a lead too far?
Leads break once the distance between the two ends exceeds 12 blocks (16 for a happy ghast), dropping the lead as an item on the ground.
Can I attach a lead to more than one mob?
Yes, leads can be chained between multiple mobs, or attached to a fence post, letting you tether several animals together or to a fixed point.
Can leads be used underwater or in the Nether?
Leads work in any dimension and can leash aquatic mobs as well as land-based ones, as long as the distance limit is respected.