User Tbale Tenant_Id

User Tbale Tenant_Id

  

when I want to create a new user , But I don't know what is this Tenant Id 

I want to know why the system will auto  to save this value . coz  about this field,i input nothing 

in the development environment , when  i create new user . this tenant_id  will save '18'

but  in the test environment , i create new user ,this tenant_id will save  '93'