The Star Destroyer is a massive space craft that can contain tens of T.I.E. Fighter and is able to bring inside itself other crafts such as the Tantive IV as seen at the beginning of Star Wars IV - A New Hope.
Star Destroyers appeared during the civil war between The Old Republic and the Separatists. They first appeared at the end of the Star Wars II - Attack of the Clones when the Senate attacks the Separatists that were having a meeting on Geonosis. They were used to move Stormtroopers to the planet in aid of Padme Amidala and her two Jedi guardians (Anakin Skywalker and Obi-Wan Kenobi) who had been captured by the Geonosians and were being fed to some creatures in a giant amptitheatre.
In the follow up film, the Star Destroyers are seen in battle over Coruscant, the capital world of the galaxy. Anakin Skywalker and Obi-Wan Kenobi are seen flying round the crafts as they seek to rescue Vice-Chancellor Palpatine from General Grevious.
The bridge of all the Star Destroyers are all much the same. The viewing area is above where most of the people work. Only the commanders and senior personnel walk at the top where they can view ahead. The picture shows Darth Vader with Emperor Palpatine and the other man is Grand Moff Tarkin.
At the beginning of New Hope, the Tantive Iv is seen being chased by a craft that goes on and one for ever. It is a ship that is parodied in Paul at the end of the film rather than at the beginning.
Even given its size and protection, its not immune from its bridge coming under attack from a lone A-Wing craft that is out of control as is what happened in Return of the Jedi.
The Star Destroyer whilst big is nothing compared to a Super Star Destroyer or the Death Star. One Star Destroyer is captained by Darth Vader. The Star Destroyer can work on its own or a fleet of Star Destroyers when they attacked the planet of Hoth.
In the Star Wars - The Force Awakens, the Galactic Empire has now become the First Order and their Star Destroyers have been given a make-over.
All the star destroyers as above are all tiny allegedly compared to Supreme Leader Snoke's Star Destroyer. Unlike all the other Star Destroyers, which are long by length, this one is wider than any other. It wider than the other are long. It is sometimes referred to as a Mega Star Destroyer on account of its size.
Even given its size, it is not immune to being destroyed by a freighter slicing it in two when the freighter captained by Admiral Amilyn Holdo slices through whilst carrying out the jump to hyperspace.