MATLAB: What does this format mean

Hello
I found the following format in one of matlab cod
[~,best] = min(X);
can anyone tell me what is [~,best] mean and why he used bracket while min returned single value

Best Answer

[min_value,index] = min(X);
% min-value is the min value and index is its index
[~,best] = min(X);
% gives only the index