At USV, we talk a lot about our investment thesis.  The USV thesis is a set of ideas that has guided our investing over the years.  It is a tool we use to help ourselves know what to look for, and to help companies who fit into it to find us.

Despite all of the writing we have done on the thesis over the years, some parts of the it remain understood, but unwritten.  One of those is what I like to call "The Butter Thesis".

"Butter" is the term we use to describe interactions & experiences that are just so smooth.  Rich, easy, delicious.  Hard to define formally, but you know it when you see it / feel it.

Butter can apply to dev tools, enterprise/b2b products, and consumer products.  

Classic examples of Dev Butter are the Stripe API and the Twilio API.  Tools that are just so simple and fun to use (and useful!) that you just can't help build with them.  Or, the first time you install Cloudflare and your site just gets fast and the DDOS just stops.  OMG Firebase. Takes my breath away.  Or before that, Ruby on Rails and jQuery.  The category-defining tools of each era of development have succeeded in large part because of their Buttery-ness.

B2B Butter is Airtable and Slack (and really, Google Docs, though that's less exciting somehow).  Or in narrower vertical, Splice.  Or, in a hidden horizontal, Carta.  Tools that make working together so so much easier -- like, hard to imagine what it was like before they existed.

On the consumer side, Butter means end-user experiences that are frictionless and joyful.  For example, I recently went to China and was blown away by the QR Code experience -- straight butter wherever you go, linking the real world to the online world.  Duolingo is Butter for Learning.  Nurx is Butter for Health.  Coinbase is Butter for Crypto.  Amazon Prime is Butter for e-Commerce.

Building for butter means understanding that every step of the experience can be honed, smoothed and improved, to the point that it's so good you just can't take it.  Butter is deceptively simple. A single ingredient that yet does so much. 

Sounds easy, doesn't it?!  Maybe this is obvious and isn't that deep. But it is hard to pull off, and truly extraordinary when it is accomplished.