what is volcano? describe its parts

Hii!
A valcano is defined as the opening in earth's crust from where, lava or volcanic ashes escape and come out and also gases are released.
There's a liquid magma which contains dissolved gases and and they rise through earth's crust.  The gases bubble when pressure decrease and magma is released out, which is called eruption.
The main parts of Valcano are - magma chamber, vents, slopes, craters and conduits.
Hope this helps.
Good luck!