Errors are normal. Do not panic. Read the log message carefully.
Common Critical Errors
! Missing $ inserted.
Cause: You used a math symbol (_, ^, \alpha) in normal text.
Fix: Wrap it in dollar signs: $x_2$.
! Undefined control sequence.
Cause: A typo in a command (e.g., \sectionn) or missing package.
Fix: Check spelling or add \usepackage.
Runaway argument?
Cause: Missing closing brace }.
Fix: Check your brackets match.
Warnings (Yellow)
Overfull \hbox (10.2pt too wide)
Text is protruding into the margin. Usually caused by long words LaTeX can't hyphenate.