The Swiss system may be used when it is not possible to play as many rounds as required in a round-robin, but it is not desired to eliminate any players before the end of the qualification. 

The first round all players are drawn at random (optional top players can be seeded) Each player then proceeds to the next round and faces the opponent following him in the ranking against whom was not played yet. 

No player is paired up with the same opponent twice. 

For an individual ranking of players who are equal on points the “Buchholz system” is used. 

Buchholz factor

The “Buchholz system” was developed to rank players who are equal on points. 

The buchholz-factor (B1) of a player is the sum of the points of all opponents played against

The buchholz-factor (B2)  is the sum of the points of the opponents of your opponents.

If you had opponents which won all games your buchholz-factor is much higher than the buchholz factor of a player who played teams which lost all games. 

The player with the higher buchholz-factor had better opponents and will be ranked higher when points are equal.

The advantage of the system

The playing ability of the opponents will become nearly the same from round to round. 

The tension will build up towards the end of the tournament.

You will get a more precise ranking to seed the competitors in the elimination round. 

It is a non-elimination format which can be used by unlimited competitors and all will have the same amount of games. 

A tournament can easier be scheduled