ATH and ATL
ATH and ATL are abbreviations used to denote the extreme price levels of a crypto-asset. ATH (All-Time High) is the highest price ever reached; ATL (All-Time Low) is the lowest historical price.
They are descriptive data, referring to the past, used as a reference to frame the historical behaviour of a crypto-asset. They do not provide any indication of future prices: the fact that an asset has reached a certain ATH does not imply it will reach that level again.