NB - I have the whitepaper pulled up now and can see what an input is, but the wallet does not tell me this, nor does it allow me to chose to send my newest coins should I wish to conduct a transaction.
Inputs/outputs/addresses are all pretty fundamental aspects of blockchain and I regularly encourage participants in crypto to take 5-10 minutes to read some wikis on them. IMHO it only takes that long to get the basic concept, and it's very good knowledge to have if you are involved in this space. (A thorough, in-depth understanding would take much longer for most people--however that is not really necessary or as much positive cost/benefit, IMHO.)
The semi-short answer is an input is an incoming amount to an address.
Well I'm thoroughly flummoxed now...
My wallet now holds 1001.9 TZC obtained through 192 mining payments to 2 addresses, and the last payment was a little over 48 hours ago so the minimum age of an input should be >2 days. The Penrose triangle, however, reports 148 inputs weighing 10178 coin days, of which 52 inputs are minimum age, 1 input is average age and 95 inputs are max age; so 148 inputs vs. 192 payments, and last payment was 2 days ago but still claiming that 52 inputs are minimum age. To muddy matters even more, the TZC whitepaper says that the minimum age for an input is 1 day, so is it any wonder that I am confused at this point?