My understanding is that at a certain point, there are taxes or regulations or something on gifts. Like if I were going to give my friend $500,000, for whatever reason this isn't as straightforward as giving him $50.
What should I know about this?
This depends on the country(ies) involved.
US citizen/resident giving gifts is required to pay a gift tax. The recipient of the gift, however, pays nothing. The value of the gift at the time of the gift-giving is used to determine the tax, and an exclusion of $14000 per person per year (as of 2013) is available to allow smaller gifts to be given without too much of a red tape. There's also a lifetime exemption which is shared between the gift tax and the estate tax. This exemption is $5.25M in 2013.
The reason the gift tax exists in the US is because the US tax code is very aggressive. This is basically double taxation, similarly to estate tax. Gifts/estates are after-tax money, i.e.: income tax has been paid on them, yet the government taxes them again. Why? The excuse is to disallow shifting of income: if one person has high income tax brackets, he may give some of his income-producing property to another person with lesser brackets who would then pay less income taxes (for example, parents would transfer property to children). Similarly capital gains could be shifted. Generation-skipping tax is yet another complication to disallow people use gifts to avoid estate taxes: a grandparent would gift stuff to grandchildren, thus skipping a level of estate taxes (the parents in between).
In other countries the tax codes may be less aggressive, and not tax gifts/inheritance as this money has been taxed before. This is a more fair situation, IMHO, yet it means that wealth moves from generation to generation without the "general public" benefiting from it.
So if you're a US person and considering giving or receiving a gift - you need to consult with a tax adviser about the consequences. Similarly with other countries, if you are subject to their tax laws.
This forum is not intended to be a discussion group, but I would like to add a different perspective, especially for @MrChrister, on @littleadv's rhetorical question
"... estates are after-tax money, i.e.: income tax has been paid on them, yet the government taxes them again. Why?"
For the cash in an estate, yes, that is after-tax money, but consider other assets such as stocks and real estate. Suppose a rich man bought stock in a small computer start-up company at $10 a share about 35 years ago, and that stock is now worth $500 a share. The man dies and his will bequeaths the shares to his son. According to US tax law, the son's basis in the shares is $500 per share, that is, if the son sells the shares, his capital gains are computed as if he had purchased the shares for $500 each. The son pays no taxes on the inheritance he receives. The deceased father's last income tax return (filed by the executor of the father's will) does not list the $490/share gain as a capital gain since the father did not sell the stock (the gain is what is called an unrealized gain), and so there is no income tax due from the father on the $490/share. Now, if there is no estate tax whatsoever, the father's estate tax return pays no tax on that gain of $490 per share either. Would this be considered an equitable system? Should the government not tax the gain at all?
It is worth noting that it would be possible for a government to eliminate estate taxes entirely, but instead have tax laws that say that unrealized gains on the deceased's property would be taxed (as capital gains) on the deceased's final tax return.