Material advantage -- is the most obvious and persistent type of advantage. Quite often it is not easily lost unless a drastic blunder is made.
In order to check who has the material advantage it is enough to compare who captured more material or who has more material left on the board.
When counting the material one should use the relative value of pieces as described  on the Basics page. This advantage can be counter-balanced by weakness
of King's position or by extreme examples of spatial advantage.

When possessing the material advantage:

1. Trade of pieces is advantageous to you. It is easier to win when there are fewer pieces remaining on the board.
   Avoid too many pawn trades.
   

   This an initial position where White was given a free Bishop. A strong player can still trick a weaker player.	After many trades position simplified. White was able to keep the Bishop and his opponent has practically no chance.    (+ -) "Decisive advantage for White"	This was the only chance. Once the last pawns were traded a position where despite an extra Bishop a mate is impossible was reached. Draw.

2. Another way to realize the material advantage is to create an attack on opponent's King. Overwhelming forces should be able to break thru.



In this game Anderssen, Adolf--Mayet, Carl. 1851 Anderssen has just taken Mayet's Knight on e5. Mayet was unable to recapture because of mate. So temporarily Anderssen has 2 extra Knights close to Mayet's King. Here is what happened: 1)Ng4 (attacking Queen on f6 and opening a line for his rook on e1 his Rook) fxg4 2)Re7+ ! Qxe7 3)Qg6+ Kh8 4)Qxh6+ Qh7 5)Ng6 mate.

When playing against extra material.

1. Complicate the position and and avoid trading pieces. As suggested above try to compromise opponent's King. Trade pawns. As shown above try to get the drawn position shown in the last diagram of paragraph 1.

   In this example from my game. Averbukh, Alex--Mandizha, Farai I have an extra Knight. (my opponent sacrificed a Knight on f2) However I am clearly lost since my King is wondering around under attacks of Black pieces and they will easily mate or win material back.