"Archival" inks and tapes do not mean that any of these products are "friendly" toward photographic papers and emulsions. The archival designation usually means that the ink is indelible and will not fade in time or the tape is not likely to come off or otherwise deteriorate with age. These inks can nonetheless migrate into the emulsion and those tapes can injure the base of fibre-based papers.

I give this advice with, as they say nowadays, "with an abundance of caution" simply because I don't want to see anyone accidentally deface, damage or ruin any photograph that may have sentimental, monetary, or family historical value.

Some folk around here will advise throwing caution to the wind and just go ahead and write on the back of prints with any old whatever..! Frankly, I have many many old snapshots headed down to me over the years will all kinds of writing on the back. With some, there were no issues and others are badly defaced by absorbed ink and "embossing" from too much pressure from a ball-point pen. In some cases, the ball-point ink became adhesive and stuck to other prints. Over the years, many clients have brought me images for copy and restoration work that have been damaged by inks and other adhesives.

At the end of the day, it is up to the OP to sort out the various advice and do what he feels is best.

Good advice!

I've scanned or copied thousands of other peoples' photo prints for class reunion slide shows. lifetime retrospective biographies, and corporate awards night videos. There is no end to the list of ways folks deface photos without knowing that they are doing so. Sometimes it takes years for damage to show up, as in acid transfer from album pages to photos mounted in or on them.

Paper clips, tapes, rubber bands, and ballpoint pens seem to do the worst damage, outside of water, sunlight, and air pollution. Acidic paper or PVC album pages are also big offenders. If you want photographic prints to last, keep them in acid free pages, in acid free binders, in a dark place where the temperature and humidity remain stable.

If you want color to last, get pigment-based inkjet prints made on fiber-based, and baryta coated papers.

There are plenty of archival preservation materials available to photographers. Just use a search engine and you'll find them.