Join

Join[l1, l2, ...] joins the lists into a single list.

Attributes[Join] := {Flat, OneIdentity, Protected}

Simple examples

In[1]:= Join[{a}, {b, c}]
Out[1]= {a, b, c}

In[2]:= Join[]
Out[2]= {}

In[3]:= Join[foo[a], foo[b, c]]
Out[3]= foo[a, b, c]