Have you ever cleared your phone’s cache (pronounced as cash + é) to free up space or boost performance, only to wonder—what exactly is cache, and why does it matter? Worry not, I am here to answer all such queries related to cache.
The concept behind cache was introduced by the British scientist Maurice Wilkes in 1965, however at that time cache was referred to as “slave memory”. Wilkes introduced this concept in his paper titled “Slave Memories and Dynamic Storage Allocation”. The core idea behind this “slave memory” was to create a faster layer of memory that could store frequently accessed data, thus improving overall system performance. IBM’s Model 85 became one of the first computers to utilize the concept of cache memory. Cache memory is now a fundamental part of computer architecture, used in CPUs, web browsers, and other applications to improve performance.
Let me explain to you the idea behind cache with a simple example. Imagine you're researching a topic and need to refer to multiple books and journals. The best place to find them is a library, but going back and forth every time is inefficient and time-consuming. A smarter approach? Borrow the most useful books and keep them on your study desk. This way, you have quick access to key resources without repeatedly searching the library. Plus, you avoid wasting time skimming irrelevant material.
In this scenario:
Your study desk = Cache (temporary storage for quick access)
The library = Main data source (original storage, like a server or database)
The borrowed books = Frequently accessed data (what your app needs regularly)
Cache works the same way—it stores often-used data nearby so your system doesn’t have to fetch it repeatedly, saving time and improving performance. Going back to our library vs. study table analogy, there are a few important things to keep in mind when using cache effectively:
Limited Space, Smart Allocation - Your study table (cache) has limited space—you can’t keep every book (data) on it. Thus, the best strategy would be to keep only the most relevant books—those you refer to frequently. Similarly, cache should store highly accessed data to maximize efficiency.
Timely Cleanup - Once you’re done with a book and won’t need it soon, remove it from the table to free up space. Likewise, cache should deallocate data that’s no longer needed, making room for more relevant entries.
Now let us understand why and how some of the common applications around us use cache:
Web Browsers (Chrome, Firefox, Edge) - Browsers use cache to store static resources like images, CSS, and JavaScript files locally and keep frequently visited webpage elements in memory. It helps in faster page loads when revisiting sites and reduced bandwidth usage. So when you revisit a news site, the logo and layout load instantly from cache.
Social Media (Instagram, Facebook) - These platforms use cache to pre-load our feed content, store profile pictures and stories and cache trending hashtags and posts. This helps in smooth scrolling experience and works better in low-network conditions. This overall helps our feed load instantly when reopening the app.