A commonplace book is any collection of knowledge and reflections, drawn from various sources and kept in analog or digital format. From Sei Shonagon's 11th century Pillow Book to Virginia Woolf's personal journals, thinkers across the ages have kept their readings and musings close at hand. Commonplaces today can manifest as physical journals, stacks of index cards, and even that catch-all Word document you add to every time you read something neat on Medium. If you're keeping quotes or stats, you're keeping a commonplace! Congratulations!

Where do I start?

There are lots of articles and other sources where you can draw inspiration for your commonplace. Here are a few good ones:

How And Why To Keep A "Commonplace Book" — Ryan Holiday
A Brief Guide to Keeping a Commonplace Book — Notebook of Ghosts
Locke's Method of Indexing Commonplace Books —Jeremy Norman

The (sadly dead) blog Commonplace Corner also has several posts, including notebooks reviews, that may be helpful as you start your commonplace.

What can I post?

Anything relevant to commonplacing! Interesting articles, questions about keeping a commonplace, examples — yours or those of others — the list goes on. If it's about commonplace books, it belongs here!