‘ATL’ stands for ‘all time low.’ It refers to the lowest price or value that an asset or item has ever been at.
For an asset such as a cryptocurrency, all-time low would refer to the lowest price that the token was ever traded for, while for an item, it could refer to a low yield of crops during a drought. It is the opposite of an all-time high and depending on where it is it the life cycle of that asset it could mark a turning point in its overall value.
For instance, for Bitcoin, its ATL was at its inception. Although it has fluctuated greatly over the years, its overall value has increased exponentially. This contrasts to other currencies such as the Zimbabwean dollar, which had its all-time low in August 2005, when one USD was purchased for $45,000 Zimbabwean dollars on the illegal black market. Although the value has since improved drastically, it is unlikely that it will ever fully recover. It is due to the unreliability of the currency’s value that the locals generally trade in other currencies such as the USD and the South African rand.