Board Thread:General Discussion/@comment-7405885-20130327134851/@comment-10688548-20130327155151

Bytes are units of information: computers think and store all the files on your computer in terms of zeroes and ones, eight of which (01001100 for example) makes up one byte.

"It" and "something" are not terribly specific or helpful to a diagnosis of what you're talking about though... Are you editing a page? An increase of 354 bytes in the size of the page is a moderately large, good increase.