Hhello everyone. I have this string here:
Is it a cipher? I've tried to decode it as a cryptogram. It didn't work. How do I know if something is a cipher?
I guess you mean "ciphertext".
There's no way to know. First of all the string is simply too short to extract any information at all from it, without knowing it's purpose. And encryption-algo's have the exact job of obfuscating the meaning of the content. This is done by applying a transformation that maps the data to a (pseudo) random bitstring. And randomness is basically just the lack of possibilities to deduct any knowledge from data. This might be just some random string or a hash or some identifier or the start of an arbitrary file or in fact an encrypted string.
Randomness is a lack of information. This is exactly what crypto attempts to accomplish; turning information into something at appears to just be randomness.