How to give double line spacing between paragraphs?

Question

I am preparing my thesis with single line spaced, but it needs double line spacing between paragraphs. I am using \\ at the end of paragraph to achieve this. How to do this by using \parskip package for the whole document?

\begin{document}

\section{Introduction}
In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network     gracefully and increases availability. \\

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in\\

 This protocol can be viewed as specialized version of ring and tree    protocol.
 As compared to other protocols, wheel protocol can be used for arbitrary     number of nodes.

 \end{document}

Answer 1

\documentclass[12pt,a4paper]{article}
\setlength{\parskip}{2\baselineskip}
\begin{document}

\section{Introduction}
In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network     gracefully and increases availability. 

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in

 This protocol can be viewed as specialized version of ring and tree    protocol.
 As compared to other protocols, wheel protocol can be used for arbitrary     number of nodes.

\end{document}

Answer 2

You can use

\setlength{\parskip}{12pt}

to achieve a custom \parskip in your whole document. Adjust the value to your needs and place the command inside your document-environment.

Answer 3

Never use \\ at the end of a paragraph and do not change the \parskip manually (see https://tex.stackexchange.com/a/14565/43317).

You could load package parskip

\documentclass{article}
\usepackage{parskip}
\begin{document}
\section{Introduction}
In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network     gracefully and increases availability. 

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in

This protocol can be viewed as specialized version of ring and tree    protocol.
As compared to other protocols, wheel protocol can be used for arbitrary     number of nodes.

 \end{document}

---

Or you could use a KOMA-Script class with option parskip=full-:

\documentclass[parskip=full-]{scrartcl}
\begin{document}

\section{Introduction}
In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network gracefully and increases availability. 

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in

This protocol can be viewed as specialized version of ring and tree    protocol.
As compared to other protocols, wheel protocol can be used for arbitrary     number of nodes.

\end{document}

See the KOMA-Script documentation to find more possible values for option parskip.

If you want to use a parskip that differs from half or full you can use the command \setparsizes{<parindent>}{<parskip>}{<horizontal white space at the end of a paragraph>}.

Example with a parskip of 2\baselineskip:

\documentclass{scrartcl}
\setparsizes{0pt}{2\baselineskip}{0pt plus 1fill}
\begin{document}

\section{Introduction}
In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network     gracefully and increases availability. 

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in

This protocol can be viewed as specialized version of ring and tree    protocol.
As compared to other protocols, wheel protocol can be used for arbitrary     number of nodes.

\end{document}

If parskip should depend on the fontsize you can try option parskip=relative additionally:

\documentclass[parskip=full-,parskip=relative]{scrartcl}
\begin{document}

\section{Introduction}
In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network     gracefully and increases availability. 

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in

This protocol can be viewed as specialized version of ring and tree    protocol.
As compared to other protocols, wheel protocol can be used for arbitrary     number of nodes.

\rule{\linewidth}{.4pt}
\tiny
In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network     gracefully and increases availability. 

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in

This protocol can be viewed as specialized version of ring and tree    protocol.
As compared to other protocols, wheel protocol can be used for arbitrary     number of nodes.
\end{document}

Answer 4

You can add the following to the top of your file:

\documentclass[parskip=full]{scrartcl}

This way, the spacing will automatically update based upon the font size you choose.

Here is a MWE:

\setlength{\parskip}{12pt}

\begin{document}

\section{Introduction}

In a distributed database system, data is replicate of the most important advantages of replication is that it masks and tolerates failures in the network     gracefully and increases availability.

In case of multiple access a problem that must be solved while using replication is about maintaining the a generalization of the majority consensus method presented in

This protocol can be viewed as specialized version of ring and tree protocol.
As compared to other protocols, wheel protocol can be used for arbitrary number of nodes.

\end{document}