Here are four different technolgies to save data for backups.  The best options to save data depend on your preferences for speed, security and cost.

#1 Save data to an online backup service

Advantages:
-    To save data in remote a location from your home or business means that in case of fire, flood or theft, your data is in a safe location.
-    You can save data anywhere where there is internet connection.
-    No initial or ongoing hardware cost to the user.

Disadvantages:
-    Slow.  To save data from videos or other large files you will need to plan on hours of transfer times for many internet services.  An internet service of 768 Kbps is about 1/1000 of the speed of a USB 2.0 external hard drive and 1/10,000 the speed of a USB 3.0 hard drive.
-    Recurring costs.  Most online data services charge a monthly fee depending on the amount of data you wish to save.
-    Privacy.  There are many services that allow you to save data online for free, but there is always the question of the integrity of the company.  Free services to save data online have to recover their costs through advertising or selling other services to you.

#2 Save data to an external hard drive

Advantages:
-    Speed. You can save data across a high-speed USB cable at speeds up to 640 MB per second with USB 3.0 drives. An internet service of 768 Kbps transfers data about 1/1000 of the speed of an USB 2.0 external hard drive and 1/10,000 the speed of a USB 3.0 hard drive.
-    Size. An external hard drive can be found with 2 or 3 terabytes of capacity to save data.  If a laptop computer disk can save about 500 GB of data, then the external drive is 4 to 6 times the total capacity of the laptop's hard drive.
-    Portability.  An external hard drive is less than the size of a paper back novel.  Some extremely portable units are the size of a cell phone.
-    Cost.  The amount of money per MB to save data to a hard disk drive is probably less than the cost of buying a stack of DVDs or purchasing an internet backup service.

Disadvantages:
-    Location.  It is up to you to make sure that the data you save is stored in a safe location.  If you save data for your small business, then you should take your portable disk drive home or send it to an off-size storage facility.
-    Fragile.  Hard disk drives can be damaged if dropped. 

#3 Save data to bank CDs or DVDs

Advantages:
-    No initial hardware costs.  Most standard laptop and desktop computers have built-in CD/DVD writable disk drives.  Your computer is likely already equipped with the disk drive you need in order to save data backups.  There is no excuse to not make backups of your important documents, photos and music on an occasional basis.
-    Multiple backups.  If you save data to your CD/DVD drive on a regular basis, you will be creating multiple versions of your data.  If a previous backup is lost or damaged, you will likely have other copies to fall back to.

Disadvantages:
-    Relatively small.  DVD disks can save up to 4.6 GB of data.  That is enough for one full-length movie in the standard DVD format or 5 or 6 movies in some of the other video formats.  But too backup an entire collection of 1000 mp3 songs (4 MB each) will require about 1 or 2 DVDs.
-    Slow.  An 8x DVD recorder will save data at 10.57 MB per second.  A DVD drive is 1/100 the speed of a high speed USB 3.0 disk drive.
-    Reliability.  DVDs are notorious for being unreadable.
-    Multiple Disks for one backup.  If you save data that is more than 4.6 GB, then your backup will span several DVDs.
-    Ongoing purchases of DVDs.  A writable DVD can be used exactly once.

#4 Save data to flash drive

Advantages:
-    Portability.  USB drives (which also go by the names of jump drives, pen drives, keychain drives, memory sticks) are small.  You can carry them in your pocket and connect them to virtually any device.

Disadvantages:
-    Limited Storage Size.  Most USB drives are relatively small.  2 GB to 16 GB is typical which is about the size of 1 to 4 DVD drives.