The 912 was a rear engine, rear wheel drive car with a flat 4 engine. It was the cheaper alternative to the 911, making it more of a true successor to the famed 356, which had been sold at a far lower price than the 911.
The 912 proved to be quite popular with the sports car crowd. Nearly 30,000 of them were sold during its 5 year run.
The 914 would replace the 912 as the entry level Porsche in 1971. The Porsche 912E was introduced in 1976. About 2,000 of them were made, and they were not sold outside of the United States. It might be the only Porsche that can make that claim. It was just a placeholder car that gave Porsche some time to finalize the design of the 924, the replacement for the 914. The 912 is the only Porsche that replaced the car that had previously replaced it.
The Porsche 912 is a classic sports car that is sought-after by many collectors today. If you would like to buy a 912 the easiest place to find one is on eBay. They also have parts on there.