Selected notes on renewing your passport. This information summarized 04June2022 from travel.state.gov and from usa.gov
See also this travel.state.gov page for detailed answers (FAQs)

You can renew your passport online if all of these are true:

1. You have your passport onhand to mail with application
2. Passport is undamaged other than normal wear-and-tear
3. Passport was issued when you were 16 or older
4. Passport was issued within last 15 years
5. Passport was issued in your current name or you can document your name change

Here are the steps. Go to travel.state.gov for specifics

1. Fill out DS-82
2. Submit your most recent US Passport
3. Include any applicable name change documents
   • a certified copy of your marriage certificate, or
   • a court order of your name change
4. Provide a photo
   • taken within 6 months of submitting your application
   • and look like you do now
   • be exactly 2“x2” (51 x 51mm)
   • USPS some offices take passport photos
     • $15 fee
     • Lexington, Bedford, and North Waltham offices take photos
     • You must make an appointment in advance
   • AAA takes passport photos
     • $10 for basic members
     • $15 for nonmembers
     • Premier members get 4 free sets/household/year
     • No appointment required
   • Best if you wear non-white clothing
5. Calculate fees
6. Mail completed application
7. Track your application status

• You must mail your DS-82 yourself.
  • Mail using USPS with a trackable delivery method.
  • Don't use UPS, FedEx, or DHL as they can't deliver to POB.
  • Postal employees should not review your DS-82 and supporting docs
• OK to renew your passport before expiration
  • Best to renew 9 months before it expires
• You can send multiple renewal applications in one envelope
  • You and spouse can send both applications in the same envelope
  • You can pay for both using one check
  • Just be sure to add up the fees correctly!
• After printing your new passport, they will send you your new passport and return supporting docs
  • These may come in two separate mailings
  • There may be a 4 week delay between receiving the new passport and getting back your citizenship documents
• Your new passport will have a different passport number
  • Be sure to update any DHS Trusted Traveler account with the new passport info

There's more FAQ on this travel.state.gov site

• Mail DS82 for routine service to this address
  • National Passport Processing Center
  • Post Office Box 90155
  • Philadelphia, PA 19190-0155
• Include
  • One recent passport photo
  • Correct passport fees, $130/passport, payable to “U.S. Department of State”
  • Most recent U.S. Passport Book
  • Printed, signed, and dated DS-82
    • single sided paper
    • compare to what's on the screen
    • make sure all data blocks and barcode appear clearly and in the same format