What is memcached?

Memcached is a tool that makes websites and applications faster by keeping frequently used data in memory, so it can be retrieved instantly instead of going back to a slower database every time. Think of it like a quick-reference notepad sitting next to your desk: instead of walking to the filing cabinet (your database) every time you need a document, you grab it from the notepad if it is something you have already looked up recently. At a high level, it works as a simple key/value store. You hand it a piece of data labeled with a name (a "key"), and it holds onto that data in your computer's RAM. When your application needs that data again, it asks for it by name and gets an immediate answer. It is designed to run across multiple servers, so as your application grows, you can add more machines to hold more cached data. It handles many requests at once using a multithreaded, event-based design. The people who would use this are developers and engineering teams running web applications that get a lot of traffic and need to stay snappy. For example, if you run an online store, the product details for your most-viewed items could be stored in the cache so that every time a shopper loads a page, the server does not have to run a full database query. This keeps pages loading quickly and takes pressure off your main database. One notable thing about the project is its strict focus on memory only. The README is clear that it should never go to disk, because the entire benefit is speed from keeping things in RAM. If the data gets swapped out to your hard drive, you have lost the whole point. It also includes an optional security feature on Linux that restricts what the process can do, adding a layer of protection. It relies on a library called libevent to handle its network communication efficiently.