I was going through an article on kaggle blogs. Repeatedly, the author mentions 'LB score' and 'LB fit') as a metric for effectiveness of machine learning (along with cross validation (CV) score).
With a research for the meaning of 'LB' I spent quite a bit of time, I realised that generally people directly refer it as LB without much background.
So my question is - What is a 'LB'?