Vinyl pressings come in various weights. The heavier the record, the longer the press cycle, the more expensive that record is to produce. A standard record typically weighs 120 to 140 grams. A heavy record is in the 180 to 200 gram range. If you take these records out of the package and weigh them, they will always weigh at very least, the weight advertised.
A heavier weight record is thicker and therefore allows for deeper grooves and more dynamic mastering. Since the vinyl is heavier- it is typically better for tracking. The 180gram record is usually flatter and quieter than a regular weight record.