The Stream 13-c029nl has an SSD storage media which is better than most portable PCs of this spec and age. Most notebook PCs that have been available for a comparable time to it have an HDD storage media. Flash drives store data in semiconductors on a circuit board rather than using magnetic or optical media. Flash have no moving parts which makes them very fast and reliable.
This laptop's storage medium (SSD) is in fact the best storage medium across all laptops that came out more than a year ago.
The worst storage medium across similar types of laptop is HDD.