Buy-And-Hold is a common label of the simplest trading strategy available; buying a security and holding on to it without trying to sell for quick profits and the re-buying at a lower price.
Most private savings strategies can be said to be buy-and-hold strategies.
The term is mostly used in combination with trying out trading systems using some kind of technical analysis software.
The oppositoe of buy-and-hold is short term based trading such as swing-, momentum-, or contrarian trading, all part of day or near day trading strategies.