I was talking about online shopping.
If you've gone to Mass that day, you're 90% of the way to keeping the day holy. Unless you spend the rest of the day digging ditches needlessly, there's no need to be scrupulous about how you spend the rest of the day.
I've even heard people ask if you can play sports on Sunday, because you break a sweat. Actually some have said you CAN'T, because it seems too much like work. Pass the remote.
We don't have to sit on the couch all day, be lazy, or watch TV to properly "rest" on Sunday! That makes a mockery of God's Third Commandment.
It is quite easy and pleasant to sit at our comfortable desk and browse eBay or Amazon.com and even purchase stuff. We can click computer mice on Sunday without breaking the Sunday rest. The prohibition on shopping is only on the presumption that you are making OTHER HUMAN BEINGS work -- and every human being has an obligation to keep the day holy, including attending Mass. Up until 1997 or so, that was a safe assumption. Not anymore, in the case of online "shopping".
We can also engage in works of culture, such as music, art, acting, writing, philosophy, computer programming (game writing), or anything else you NORMALLY DON'T HAVE ENOUGH TIME FOR, BECAUSE YOU'RE WORKING. Anything "mental" is automatically fair game. Anything you'd think of as a "hobby" -- learning how to put guns together, wood carving, sculpting, even taking engines apart. As long as it's not for pay, and mostly learning/mental/for the fun of it, it's fair game. if you really want to have time for it, but you normally have to work instead, that's a sign that you can do it on Sunday.
It's only SERVILE "work" that is prohibited.
Again, we must keep the spirit of the law. Sunday should be a day different from all the others. But this difference lies CHIEFLY in our attendance at Mass, and in not working for "the man" a.k.a. for pay. We should all seek out careers and jobs that DO NOT require working on Sunday, unless the benefits (helping people as a doctor or firefighter) outweigh it, or it's obvious that's your vocation.
As a man involved in ecommerce, I'm here to tell you that a website just sits there 24/7 with no input from you or anyone else. Those orders just sit there until you get to them. Even the processing of the credit card is done by computers.
And while we're on the topic, it's only UNNECESSARY servile work and shopping that are prohibited. If you live in the country and travel to town only for Mass on Sunday, you are allowed to go shopping while in town. Everyone knows if he is (trying to) deceive God and/or himself on this matter. If you honestly never leave the house during the week for whatever reason (too busy raising family, need to merge trips, etc.) then it's not sinful to make use of that one weekly trip to pick up things you need. I know that there are people who don't work outside the home, or otherwise don't have a chance to do shopping during the week. Maybe that doesn't apply to you, and you laugh at the idea. But I'm here to tell you such exceptions DO exist. Which is why we should all give others the benefit of the doubt, and/or ask our traditional priests for guidance if you have any questions.