What does LNode* &L Mean? [duplicate]

I've been learning c++ for a while. Recently I saw a format of passing function parameters. It looks like this

typedef struct LNode { int data; struct LNode* next; } LNode, *LinkList; bool insertData(LinkList &L, int i){ cout << l; return false; } 

I know that LinkList is equivalent to LNode* which means a head pointer. But what does LinkList & aka LNode* & mean under the circumstances?

It seems to me that passing a LNode* aka LinkList would be enough.

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