RadSpreadStreaming: Update Overview article

libraries/radspreadstreamprocessing/overview.md

@@ -12,13 +12,40 @@ position: 0
 
 Thank you for choosing Telerik **RadSpreadStreamProcessing**!
 
-**RadSpreadStreamProcessing** is a library that allows you create big spreadsheet documents and export them to the most common file formats with a great performance and minimal resources.
+This article briefly explains the Spread Stream library specifics as what is spread streaming, how it works compared to the **RadSpreadProcessing** library and when to use it.
 
 ![](images/SpreadStreamProcessing-Overview_01.png)
 
+## What is Spread Streaming?
+
+Spread streaming is a document processing paradigm that allows you to create big spreadsheet documents with great performance and minimal memory footprint. 
+
+The key for the memory efficiency is that the spread streaming library writes the spreadsheet content directly to a stream without creating and preserving the spreadsheet document model in memory. Each time a value is set, the export kicks-in and the new value is written into the stream. This allows you to create large documents with an excellent performance.
+
+## Key Features
+
 Some of the features you can take advantage of are:
 
-- Export to XLSX or CSV files
-- [Styling]({%slug radspreadstreamprocessing-features-styling-cell-styles%}) and [formatting cells]({%slug radspreadstreamprocessing-model-cells%}#set-a-format)
-- Hidden [rows]({%slug radspreadstreamprocessing-model-rows%}) and [columns]({%slug radspreadstreamprocessing-model-columns%})
-- Grouping
+* Export to XLSX or CSV files
+* Writing directly into a stream
+* Append new worksheets to existing ones
+* Grouping
+* [Styling]({%slug radspreadstreamprocessing-features-styling-cell-styles%}) and [formatting cells]({%slug radspreadstreamprocessing-model-cells%}#set-a-format)
+* Hidden [rows]({%slug radspreadstreamprocessing-model-rows%}) and [columns]({%slug radspreadstreamprocessing-model-columns%})
+* [Freezing panes]({%slug radspreadstreamprocessing-features-worksheetviewexporter%}#freeze-panes)
+
+## RadSpreadStreamProcessing vs. RadSpreadProcessing
+
+There are two main differences between the libraries.
+* __RadSpreadStreamProcessing__ can be used only to create documents and append data to existing ones. On the other hand you can use the __RadSpreadProcessing__ also for reading documents.
+* __RadSpreadStreamProcessing__ writes directly into a stream, unlike __RadSpreadProcessing__ which creates models for the elements in the document. This is why the memory used with the spread streaming library is significantly lower than when using __RadSpreadProcessing__.
+
+## When to Use the Spread Streaming
+
+You can use the spread stream processing to create and export large amount of data with a low memory footprint. You can also append data to already existing document stream.
+
+## See Also
+
+* [Getting Started]({%slug radspreadstreamprocessing-getting-started%})
+* [Workbook]({%slug radspreadstreamprocessing-model-workbook%})
+* [Worksheet View Exporter]({%slug radspreadstreamprocessing-features-worksheetviewexporter%})