Computer storage media has evolved over the years following advances in technology.

Originally, secondary storage consisted of paper media. Information entered on a machine with a typing keyboard that punched holes in the media. a row or column of holes represented a character of data (in ASCII, BCD or EBCDIC format) or a set of binary bits being on or off. They were used to enter data into a computer, punch out data results, save executable programs and load them into the computer for processing

Paper tape (rolls of tape one inch wide) with columns of up to eight hole positions. Adopted for computer use, they were first used as a temporary storage and transform medium in telegraph-teletype systems.
IBM Hollerith cards had 80 columns each having 12 rectangle hole positions labeled AB0...9. Originally developed to speed up record processing in the 1890 census
Sperry Univac cards had 90 six hole columns arranged as a set of 45 columns above a second set of 45 columns.
IBM system/3 had smaller cards with 3 32-column rows labeled BA8421 for a total of 96 columns of data.

Magnetic tape is the original media that enabled high capacity backup, storage, and distribution. A long tape wound onto a supply reel is placed on a rotating hub of a drive mechanism, guided past read/write heads and a capstan speed regulator, then onto a take-up reel on a rotating hub that turns with only enough force to reduce slack and maintain necessary tension on the tape. Depending on the media and environmental conditions, there was a risk of data corruption or loss. Tapes used various methods such as parity bits, checksum, Longitudinal Redundancy Check (LRC), cyclic redundancy check (CRC) included with the recorded data to detect error data loss and even correct some of them. Devices often supported reading and writing with the tape moving in either direction. To protect the media and insure data integrity, tape was eventually packaged and maintained in sealed or enclosed protective cartridges

Half inch wide magnetic tape stored on 10 1/2 inch (or smaller) reels were also used as intermediate storage during processing on computers without any other secondary storage. Multiple tape drives were used as work areas. High speed drives used air/vacuum columns as buffers to prevent tape from being damaged or torn during high speed start/stop activity. When done, the tape needed to be rewound onto the original reel which was removed from the tape drive for storage. The back of a reel had a circular groove which, when detected by the drive hardware, disallowed writing to the tape. Insertion into the groove of a "write ring" enabled the drive to write to the tape. Tape capacity is usually measured in BPI (Bytes/Bits Per Inch), with common data densities being 800, 1600, 3200 and 6250 BPI. Tapes included a removable protective ring around the outside of the reel to prevent dust and contaminants from harming the media. An operator removed the outside ring, mounted the reel on the supply hub, threaded it part way into the devices and the machine did the rest. Later versions included an automount ring that opened in the drive, sucked out some tape which self mounted.

IBM 2321 data cell was a device that mounted several tape cartridges around a rotating drum surface. Each cartridge had a long strip of tape that was pulled down past a read/write head after rotating the drum to a read/write position. The device was regarded as a direct access device with much greater capacity than but a little slower than actual direct access disk drives.
An Automated Tape Library had one or more tape drives linked to a big box or room with hangers, slots, or holders where tape reels were stored based on some identification code. When a computer needed a specific tape, an automatic robot mechanism would locate the designated tape moved it onto a tape drive, automatically mount it and make it available to the program. When done, the tape is dismounted and moved back to its storage location.
Digital Equipment Corporation developed DecTape (or LincTape), 3/4 inch wide tape on a 4 inch reel. preformatted to fixed size blocks with embedded block identification and it enabled reading and writing by block number without affecting adjacent blocks. Data was written in a redundant manner resulting in a media with a high tolerance to damage. It was usable as a direct access device with a file directory structure, but slower.
Although not a standard data storage media, the IBM Magnetic Tape Selectric Typewriter (MTST) used sprocket fed tape cartridges with one inch wide tape with a capacity of about 24000 characters. One of the first word processing systems, it was an IBM Selectric typewriter with one or two tape control consoles. Interestingly, it had no take-up reel. Tape unwinding from the cartridge would fall into a bin beneath it and would get sucked up again when rewound. With proper control code inserted, the tapes would be used on a Magnetic Tape Selectric Composer (MTSC) to create print ready images on paper. "stop codes" embedded in the tape document would stop the composer during printing to allow an operator to change Selectric type ball fonts and continue. These tapes could also be read on an IBM 2495 Tape Cartridge Reader attached to a mainframe.
Various cartridge enclosures were developed to protect magnetic tape. Originally, cartridges held a spool of magnetic tape in a box protected from dust and other hazards. When inserted into a tape drive mechanism, the tape was drawn out onto a builtin takeup reel. When done processing, the tape was rewound into the cartridge and removed. There were also cassettes that included a tape spool as well as a takeup reel in the package with an opening for read/write processing. Cartridges and cassettes became available in various tape widths, dimensions, data capacity, and processing speed. Many competing types and styles were developed claiming more speed, more capacity, more reliability. Some were able to stream a lot of data without stopping, some had an actual file structure, some did automatic data compression/decompression. Some worked only on specific computers with proprietary interfaces and software, most were manufactured with standard interfaces (SCSI, PATA, SATA, USB) compatible with many machines. They were identified by manufacturers (such as IBM 3480/3570, DEC TK50/TK70) or based on their description such as the many versions of QIC (quarter inch cartridge), LTO (Linear Tape-Open), DLT (Digital Linear Tape), 4mm, 8mm. etc. Like tape reels, many of these tape configurations were also supported by automated tape libraries.

The disk drive or hard drive or high speed rotating surface of magnetic material allowed for high speed access of a lot of data with rotation speed (RPM), data capacity, and data transfer time (BPS) always getting better with technological advancements. Software along with controller hardware was needed to keep track of what information was in what part of the device. It then had to determine which read/write the data was going to pass under and when the data would be under the head to perform the function. Some devices had varying length blocks of data with a varying number of blocks passing a read/write head. Some had fixed length blocks and a fixed number of blocks caled sectors available for each head.

A drum storage device was a cylinder with multiple read/write heads distributed along the length of the magnetic rotating surface. Accessing data was very fast and these were often used as "swapping" areas for multiuser systems.
Rotating disk with one or more spinning surfaces (platters?). Each platter was "logically"split into multiple concentric circles called tracks and read/write head was designed to move back and forth along the surface to reach a desired track before reading/writing. To increase capacity, a device would have multiple platters stacked as a pack removable from the drive which had an assembly of read/write heads, one for each platter. The heads all moved together to simplify the design. Each set of track positions was called a cylinder and read/write positions were designated as Cylinder/Head/block or Cylinder/Head/Sector on the track. Early disk media was large (24 inch to 14 inches diameter) were removable disk pack assemblies from the disk drive which often was about the size of a washing machine. Capacity ranged from 2 megabytes to 10 megabytes to 30 megabytes and more
Portable removable disk cartridges such as the IBM 2315 and the RK05 DECpack protected a single 14 inch disk platter in a labeled enclosed plastic case. The cartridge was easily loaded or removed from a disk drive and held between 2-4 megabytes of storage. Later models had larger storage capacity.
Sealed disk drive and media went from an 8 inch form factor (standard box size) to 3.5 inch and smaller with capacity growing from 5 megabytes to gigabytes to the current terabyte capacity.
floppy drives (or diskettes) were small thin single "platter" floppy media in a square paper/plastic covering and a slit where the head actually came in contact with the read/write surface. Starting as a single side 8 inch unit used by IBM to load microcode to some mainframes, The format was adopted by the industry, expanded to using both side for data storage. The IBM System38 used single diskettes or magazine cartridge loaded with 10 diskettes, while DEC had the RX01 and RX02 cartridges included in a word processing system on a minicomputer. A 5 1/4 inch version was used for the original IBM PC, its capacity was doubled, a 3.5 inch version in a hard case was used in the IBM AT computer, and a double capacity version soon became available. They became the main storage, backup and distribution media until the development of the CD-ROM

Following the development of the large video laser disk and the audio compact disk (CD) was the use of laser technology to "burn" computer information to optical devices.

The CD-ROM (Compact Disc-Read Only Memory) was used for digital software distribution. Originally made to be inserted into a protective carrier and inserted as a cartridge into a drive mechanism, it was soon simplified into a drive with a slide out tray (sometimes confused with a cup holder) where the disc was placed and was drawn back into the drive. The first CDs transferred data at about 150 KB/sec and spun at 200 to 530 RPM. Later media and devices were faster and were measured by a multiple of the original speed. Modern ones were able to go up to 50X (50 times the original rate) and faster.
Early version of a writeable CD (WORM for Write Once Read Many) became available such as the Maxtor OC-800. It came in a protective cartridge and used proprietary hardware and software to write to the disk cartridge.
The Compact Disk Recordable (CD-R) became the standard writeable (WORM) medium requiring a device capable of writing (burning) the disc. It did not require any special cartridge or carrier. Although data CD-R was sold separately from audio CD-R, they were the same type of disc and interchangeable. The only difference between them was the slightly higher cost for the audio version for the added licensing fee to permit copying licensed audio music. Later versions were able to burn a CD-R at 50X (50 times the original rate) and faster. Both the drive and the media needed to match the same capability and not all older devices were able to successfully read devices created at the faster speed
The Compact Disc Rewriteable (CD-RW) allowed multiple erase/rewrites to the same disc. Both the disc and hardware need to be capableand compatible at the higher speeds.
DVD-ROM (Digital Versatile Disc) and Blu-Raymedia looked like but had a much higher capacity than a CD. Originally used for video recording, they were adopted by the computing industry. Drives designed to use the DVD were also made to be compatible with older CD technology.
The Writable DVD comes in severable Digital Versatile Disc-Recordable flavors, DVD+R and DVD-R, DVD-RW and DVD+RW that use different read/write technology. Newer drives are designed to read most formats but not always...

Semiconductor (solid state) media: Unlike most other kinds of solid state memory, these are designed internally so that they do not lose information when power is turned off or lost.

A solid state drive (SSD) is a semiconductor electronic devices designed to look like and be a plugin replacement for standard rotating disk drives. It has no moving parts, is supposed to be faster since their is no seek time to wait for a head to be positioned. Models are available with most of the standard hard drive connections.

USB media, memory sticks, flash drives, Compact Flash, SD (secure media) Cards, micro SD Cards, etc. are pretty much the same type of secondary storage that com in different packaging and different ways to connect to a computer. Initially available with relatively small capacity (32 Megabytes, 64 Mb) the technology now allows them to store many gigabytes of data if not terabytes. These devices are capable of being used like a random access hard drive and have a directory structure. Most can be formatted and loaded (written to) so that they are bootable (if the computer supports it). It is possible to boot and run a whole system of some of these devices.

A down side of the solid state products progress is its physical package size versus its capacity. Older offline storage (Tape, CD) allowed for labeling its contents on the outside of the medium. These barely had room for an identifying or numbering label to know which "thing" has what on it. Additionally an awful lot of data can fit in a one square inch item (or smaller). Never has it been possible to lose so much saved data in one swoop.

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