Both. I have a notebook where I record the particulars of each load I make (case, how many firings, primer, powder, charge, bullet, OAL) with comments on their performance. I use it also to record any measurements I make on various cases or projectiles. I also use a spreadsheet to record load recipes from any source (powder or bullet manufacturers, reference books, forum posts) for easy reference ("did I make a round with this OAL using this projectile and powder in the past?").