7806 is a 6V Voltage Regulator that restricts the voltage output to 6V and draws 6V regulated power supply. The 7806 is the most common, as its regulated 6-volt supply provides a convenient power source for most TTL components.
7806 is a series of 78XX voltage regulators (as known as L78xx, LM78xx, MC78xx...), the xx is replaced with two digits, indicating the output voltage (for example, the 7805 has a 5-volt output, while the 7812 produces 12 volts).
Linear regulator like 7806 has performance issues with respect to battery life and Power loss. If you are looking for an alternative for 7806 with better efficiency and less power loss, then we would recommend a DC Buck Switching voltage regulator.
Buck converters may be preferred over 78xx regulators because they are more efficient and do not require heat sinks, but they are more expensive.