Im not exactly sure what you mean by “space at each line break” so here are there possible ways to mar a paragraph’s begin.

1. Parindent
The most common way is indenting the first line of each paragraph, except it is preceded by a headline. This way is the preferred way, because it is also visible at a page break or after an equation, list etc. while the parskip becomes invisible in such cases.
Since this is also LaTeXs default (at least in the most classes) you don’t have to do anything.
2. Parskip
Another option is to leave some vertical space between paragraphs. This can be done by hand using
\setlength{\parskip}{\baselineskip}
\setlength{\parindent}{0pt}
but I suggest using the package parskip since it also cares for lists or if you using a KOMA-Script class, the parskip option.
3. Hang indent
A rather unusual way is to outdent the first line or indent all lines except the first, which can be done with
\setlength{\parindent}{0pt}
\everypar{\setlength{\hangindent}{1em}}
But this should be handled with care and is not really advisable.
Full Code
\documentclass[
% parskip = full,% better than setting the skip manually!
]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{lipsum}
% In a real document you should never mix different types and
% the settings should be made in the preamble.
\begin{document}
\section{Normal Indent}
\lipsum[1-3]
\section{No Indent: Skip between pars}
\setlength{\parskip}{\baselineskip}
\setlength{\parindent}{0pt}
% It is better to use the parskip package or
% KOMA-Script’s parskip-Option!
\lipsum[1-3]
\section{Hang Indent}
\setlength{\parindent}{0pt}
\everypar{\setlength{\hangindent}{1em}}
\lipsum[1-3]
\end{document}
Although I did for the example image these different versions should not be mixed in a single document!
\parskip. Theparskippackage can help, the KOMA classes have options to deal with that natively. – moewe Sep 04 '15 at 15:14\hspace*is a horizontal space, which you say you don't want, at least at the beginning of a paragraph. do you really mean you want a vertical space between paragraphs, or do you want paragraphs to begin with an unindented line, followed by continuation lines that are indented? – barbara beeton Sep 04 '15 at 15:20