Max_id in Twitter search api


I send to request for Twitter_search_Query like this

I get response like this

“search_metadata”: {
“completed_in”: 0.036,
“max_id”: 898090448333320200,
“max_id_str”: “898090448333320191”,
“next_results”: “?max_id=898090423930900480&q=narendramodi&count=10&include_entities=1”,
“query”: “narendramodi”,
“refresh_url”: “?since_id=898090448333320191&q=narendramodi&include_entities=1”,
“count”: 10,
“since_id”: 0,
“since_id_str”: “0”

But i will send max_id for next_query
In the above response which max_id is send to api for getting old tweets? max_id or max_id_str or max_id present in next_results.
what is use of max_id?
can we eliminate duplicate tweets using max_id?
How to use max_id parameter in Twitter_search api?

can you help me?