Asset and liability management (often abbreviated ALM) is the term covering tools and techniques used by a bank or other corporate to minimise exposure to market risk and liquidity risk through holding the optimum combination of assets and liabilities.
[1] It sometimes refers more specifically to the practice of managing financial risks that arise due to mismatches - "duration gaps" - between the assets and liabilities, on the firm's balance sheet or as part of an investment strategy.
It is focused on a long-term perspective rather than mitigating immediate risks; see, here, treasury management.
The exact roles and perimeter around ALM can however vary significantly from one bank (or other financial institution) to another depending on the business model adopted and can encompass a broad area of risks.
Often an ALM approach passively matches assets against liabilities (fully hedged) and leaves surplus to be actively managed.