Many people use PayPal to make commercial payments, for example, if they are buying things. When doing this it is a good idea to protect the payment so that if something goes wrong with the purchase PayPal will guarantee to refund your money, regardless of whether the seller wants to do so. Sellers pay a fee out of every payment to them to fund this.
However, if you trust the person you are sending money to, for example if you know them personally, you can waive this protection and no fee is deducted by PayPal: all the money that you send is transferred, at no cost to you or the person you are sending money to.
The Almanac is provided free of charge, and users are invited to make a donation. There is no sales transaction, nothing to be lost or damaged in transit to you, and nothing is given you in return for your donation. Consequently there is no need for protection, and no need for you to get PayPal to deduct a fee to protect you. By waiving your protection, 100% of your donation reaches me. If a fee is deducted then on average over 5% of your donation goes to PayPal's profit line.
You can stop a fee being deducted, by telling PayPal that the
payment is to “friends and family”. Simply click on
the button labelled “For friends and family” in the
payment window.