Thirds of a Cigar are a way that some cigar reviewers break a cigar up into sections for reviewing purposes. While it’s not an official aspect of the cigar its helpful when describing changes in flavor during a review.
The 1st third of a cigar is the section from the foot of the cigar up towards the middle of the barrel.
The 2nd third of a cigar is the middle section of the barrel.
The last third of a cigar is from the middle to the head of the cigar.