It changes the wrapper.
A file format is the way the same underlying media is packaged and encoded. Converting changes compatibility and storage behaviour more than it changes the subject itself.
Type, Layout & Effects
Case Converter.
Convert text to upper, lower and title-style case.
1 Enter2 Adjust3 Use result
Input
Answer
TOOLS FOR THE ANNOYING BITS
Upper, lower, title and sentence case ready below.
Copy the version you need.
Useful to know
Four things worth knowing.
Conversion is not enhancement.
Conversion is not enhancement. Re-encoding a poor source cannot restore missing detail, and some formats lose transparency, animation or metadata.
Check what the format dropped.
Judge it at the size it will actually be used. Typography and spacing are partly optical.
Choose for what happens next.
Choose the format for what happens next: JPG for ordinary photos, PNG when transparency matters, WebP/AVIF for web delivery, and keep the source if you may edit again.