Hotlink

https://erock.imgs.sh/what-is-a-selector

Resize width (preserve aspect)

https://erock.imgs.sh/what-is-a-selector/300x

Resize height (preserve aspect)

https://erock.imgs.sh/what-is-a-selector/x300

Resize width and height

https://erock.imgs.sh/what-is-a-selector/300x300