If something is case-sensitive uppercase and lowercase letters are treated as two different things.
This has become common since computerisation. But it is not always true. Passwords are generally case-sensitive, but email addresses are not. urls are usually case-senstive but search engines may not be.
This article uses material from the Wikipedia Simple English article Case-sensitive, which is released under the Creative Commons Attribution-ShareAlike 3.0 license ("CC BY-SA 3.0"); additional terms may apply (view authors). Content is available under CC BY-SA 4.0 unless otherwise noted. Images, videos and audio are available under their respective licenses.
®Wikipedia is a registered trademark of the Wiki Foundation, Inc. Wiki Simple English (DUHOCTRUNGQUOC.VN) is an independent company and has no affiliation with Wiki Foundation.