FAQ

Even if she is with people she knows at say home or work, she never knows when and if someone that doesn't know about her secret may pop by. So, she likely wears the glasses to be safe.

Another explanation could be, that the glasses complete the disguise of Kara Danvers, so she is used to wearing them when she's not Supergirl.

Also the lens of her glass prevents her from seeing with x-ray vision and you can notice it that she takes her glass halfway off when she want to use her x-ray vision when she is Kara Danvers.

Famously she is affected by Kryptonite, the various different forms having different negative consequences for her. She can also be weakened by exposure to the light of a Red Sun or its' facsimile. We also see her overpowered by a "Black Mercy" creature, a tentacled alien parasite which puts her into a coma by injecting her with a hallucinogen. She also proves susceptible to brainwashing by the Dominators amongst others, magic, sonic blasts and does need oxygen.

The suit protects her from Kryptonite and also allows her to operate in space. It was also a handy way to hide Melissa Benoist's pregnancy.

We have 'Red Daughter' who wears a green/grey version of the Supergirl suit with red seams. We also have 'Biazrro' Supergirl who wears the standard outfit but has grey/white skin and plain black eyes. 'Overgirl' is the Nazi version of Supergirl from an alternate dimension where Germany won the Second World War. She wears a darker costume with the "Sun rune" double lightning bolts on her chest instead of an S.

Kara was sent in a separate escape pod from Kal-El. Her pod became stuck in the Phantom Zone, where time does not pass. After twenty four years her pod left the zone and arrived on Earth.

Yes and No. Supergirl is in what is called the "Arrowverse". The "Arrowverse" is a group of shows that share continuity and who's characters interact with each other across the different shows. However within the "Arrowverse" the character of Supergirl is from a different universe and a different Earth then the characters in the rest of the shows. Within the "Arrowverse" there are multipule universes that are all slightly similar to each other in different ways. Most of the shows take place in what they call "Earth 1", Supergirl takes place in another "Earth", but can come visit "Earth 1".

There are three long-running iterations of the Supergirl character, the first being the original Kara Zor-El, Superman's cousin from Krypton, who died in the Crisis on Infinite Earths event, after DC Comics decided that Superman should be the sole Kryptonian survivor.

After continuity was rebooted, she was replaced by a protoplasmic, shapeshifter Supergirl also known as Matrix, created in another universe by that world's Lex Luthor. Matrix saved a girl named Linda Danvers and the two merged, becoming a new Supergirl. Linda eventually developed angelic powers, and after failing to save the original Kara Zor-El from her death, quit the Supergirl mantle.

After another DC universe reboot, the Kara Zor-El version of the character was re-introduced, and remains to this day.

Kara also has an Earth-2, more matured version of herself, Kara Zor-L/Power Girl.