Go: Type alias
An alias declaration has the form
type T1 = T2
As opposed to a type definition…
type T1 T2
…an alias declaration doesn't create a new distinct type different from the type it's created from. It just introduces an alias name
T1, an alternate spelling, for the type denoted by
Type aliases are not meant for everyday use. They were introduced to support gradual code repair while moving a type between packages during large-scale refactoring. The article Codebase Refactoring (with help from Go) covers this in detail.