Hard drives made with spinning platters have been a fixture in personal computers since the late 1980s. But according to a new report by the market research firm TrendForce, this will be changing over the next few years.

As early as 2018, more than half of PCs will store data on memory chips instead, says TrendForce. This is the same kind of long-term storage currently used in smartphones, tablets, USB thumb drives, and camera memory cards.

Currently, 33% of PCs sold come with this type of storage, called solid-state drives (SSDs). This is a type of “flash” memory that’s fast like a PC’s random-access memory (RAM) but retains data after the machine is turned off like traditional hard drives. In two years, predicts TrendForce, personal computers shipped with SSDs will grow to 56% of the market.

Because SSDs have no mechanical moving parts, laptops and desktops with SSDs are faster and quieter, use less power, and are more resistant to being bumped or dropped than those with traditional hard drives. But they’re also more expensive and typically have less storage space. Though SSDs are expected to continue to shrink in price as they expand in capacity, PCs equipped with them will likely still be premium priced.

SSDs also wear out as the data in memory cells are overwritten again and again. But traditional hard drives have their own reliability and longevity concerns, with a finite life also. Because traditional drives consist of read-write heads close to platters that spin at high speed, their components when malfunctioning can literally crash into one another, trashing the drive and the data on it. But traditional hard drives have become more dependable, and their average projected life currently is longer than SSDs, though SSDs will continue to become more dependable as well.

The first hard drive was introduced in 1956 by IBM. It was made for use with large mainframe computers about one ton in size, and the hard drive itself was the size of two refrigerators. The drive’s capacity was 5 megabytes, with 5 million bytes being the equivalent of 5 million letters, a million words, or four medium-size books.

Hard drives became the primary form of long-term storage for mainframe computers by the early 1960s. Before that, computers for storage used punch cards, literally pieces of stiff paper with holes punched into them at specific locations to digitally represent the data on them.

The first personal computer with an internal hard drive was the IBM PC XT, introduced in 1983, two years after IBM introduced its first PC. Its hard drive was 10 megabytes in size. A budget desktop PC or a laptop PC today can have a hard drive with a capacity of 1 terabyte, a trillion bytes, which is about 100,000 times more. The largest manufacturers of hard drives today include Seagate, Toshiba, and Western Digital.

Before PCs had hard drives, they had floppy drives, which used removable discs, first 8-inch, then 5 1/4-inch, and then 3 1/2-inch, though the 3 1/2-inch discs were stiff, not flexible like previous ones. Many earlier PCs, introduced in the late 1970s, used tape cassettes for storage. Later, Apple was the first major personal computer company to ship PCs without a floppy drive, and by 2007 just about all PCs were shipped without them.

Local removable storage was, and still is, handled mostly by USB thumb drives. The “cloud” is another other major form of storage today, where you keep the results of your document editing, photo sharing, and online backups. Low-priced Chromebooks use the cloud has their primary form of long-term storage. Cloud storage consists of many banks of traditional high-storage hard drives that are reachable over the Internet.

Along with the cloud, SSDs are a game changer. With SSDs, things started slowly. Toshiba was the first to introduce flash memory, in 1984. In 1991 SanDisk made a 20-megabyte SSD that sold for $1,000. It wasn’t until around 2007 that SSDs started becoming mainstream. Apple’s MacBook Air laptops have come with SSDs as standard since 2010. The largest manufacturers of SSDs today include Samsung, SanDisk, and Lite-On.

A random survey provides an idea about pricing today. From Newegg 250-gigabyte internal SSDs, used for upgrading your current PC, sell starting around $100, 500-gigabyte for around $160, and 1-terabyte for around $240. Best Buy sells a new Lenovo laptop with a 256-gigabyte SSD drive, 8 gigabytes of RAM, and a 15.6-inch screen for $730 and a Lenovo laptop with similar specs but a 1-terabyte hard drive for $560.