The US Postal Service, for all it's flaws, is still a pretty good service. Okay, at least you don't see as many videos on YouTube of your local mailman throwing your new monitor over the fence... But when to use who? Both now have online services, where you can enter the information about your package and print out a mail label to ship it. USPS does not require you to have an account to do this; neither does UPS, but they give you a discount if you sign up. USPS has their well-touted Priority shipping, with several different sized "If it ships, it fits" flat-rate boxes and envelopes. They provide the boxes or envelopes free of charge for that use. They also have Priority shipping boxes that do not have a flat rate, so you have a choice of sizes to use. Your post office has some of these boxes on hand, or you can order them online from the USPS at no charge. Generally speaking, if the package will weigh over 4 pounds, the flat rate box is usually the best rate you can get. It even runs cheaper than Parcel Post in most cases, until you get into bulky or heavy items - and then UPS is frequently cheaper. Major exception to that rule: USPS is cheaper to Hawaii and Alaska - UPS is dynamite in the contiguous 48, but offshore they get scary high! Internationally, USPS has First Class for relatively small/light parcels (each country has particular acceptable maximum weight and size for these), Priority or Express mail. Another critical consideration is the value of the item being shipped. USPS will sell you insurance - not the cheapest - but UPS has you covered for the first $100 of value at no additional fee. You declare the value of the item; if you have to file a claim, you simply substantiate the value with documentation of purchase or replacement value, and be sure to include that you want to be reimbursed for the shipping fee, too. I have filed claims with each service, and with photos and documentation, neither was a real problem, though UPS was quicker to respond with a check. Both USPS and UPS have websites where you can enter the package and destination data to get an estimate of the shipping fees. For online users only, USPS has four special boxes called Regional Rate boxes; they can only be ordered online and only online-produced shipping labels can be used - but they are dandy for items that fit in the moderate-to-modest size boxes and aren't going too far away. And with USPS, you can request home pick-up of any Priority or Express mail parcels, as long as your request is received by about 10pm (they changed this, and it may be later - but I always reserve by 9pm to be sure). As with everything, there are always exceptions - but for a quick reference, this will cover most needs.