Is a personal gift of several thousand dollars (say $10,000 with no strings attached) considered taxable income? If yes, are there any limits and where does TT address

[Opus 17]

Gifts received are not taxable income. 

The gift giver needs to report gifts that are more than $14,000 per person per year using a gift tax return.  Gift tax is not actually required until the lifetime gift amount reaches around $5 million, but the IRS uses the gift tax return to keep track of a person's lifetime gifts.

If the gift is from a foreign person or corporation, the recipient must file a foreign gift form (if more than $100,000 combined from foreign persons or more than $15,000 combined from foreign corporations).  Again, no tax is owed, but the IRS wants to keep watch for income disguised as gifts, and cross-border money laundering.