These are regular builds of "testing", what will be eventually released as "Buster", Debian 10.
All the installer images are distributed as ISO and jigdo files. Please use jigdo if you can, as it significantly reduces the load on our servers and it may greatly speed up your download too. The official release images are also normally available via bittorrent.
If you encounter any problems with these images, please check the Debian CDs FAQ. The most common complaint at the moment is about wrongly-sized or corrupt DVD ISO images, which is normally a bug in your http download program.
If your problem is not covered by the above FAQ, please:
debian-cd is a small team of people working on creating, testing and distributing Debian images for you. For more information about the team and how it all works, see the Debian wiki page about us.