> ## Documentation Index
> Fetch the complete documentation index at: https://docs.less.tech/llms.txt
> Use this file to discover all available pages before exploring further.
# Join Forces
One of the most useful tools in your toolbox is to merge dataset. To that end, we have a couple of quite neat tools: [Combine](/tools/merge/combine), [Stack](/tools/merge/stack) and [Append](/tools/merge/append).
The Combine tool - which is perhaps the most valuable tool out there - merges two datasets by one or multiple IDs - it's like a SQL join or a XLOOKUP/VLOOKUP in Excel. The Stack tool stacks datasets on top of each other. The Append tool attaches a number of rows and columns to a different dataset.
## Exercise
We're working with the *NATION* and *REGION* datasets and you want to get the result shown below. We end up with eleven rows and used nine tools to get the result.
Note that we use all three tools (Combine, Append and Stack) to get the result. And you should too.
1. We start by combining the *NATION* and *REGION* datasets.
2. We use a [Manual Input](/tools/utilities/manual-input) tool to create a new small dataset. It contains two rows in a column called *filter* (EUROPE and AMERICA). We attach this and use a Filter to ensure that all our rows are either in Europe or America.
3. We use a second Manual Input tool to create a new small dataset. It contains one rows with two columns *country* (value = DENMARK) and *region* (value = EUROPE). We put this dataset on top of the original combined NATION+REGION dataset.
## Solution