How to add a drop-down list in Excel? It’s a real­ly sim­ple task. 

First of all, we have to have our list (1). Then, we have to select a cell or cells to which we want to add the drop-down list (2). Then, we’re going to the Data tab (3) and click on the Data Val­i­da­tion com­mand (4) (Fig. 1)

Preparing data
Fig. 1 Prepar­ing data

In the Data Val­i­da­tion win­dow, we have to select the List option in the Allow bar, then we’re select­ing the range and write it into the Source bar. Then OK (Fig. 3)

Data Validation window
Fig. 2 Data Val­i­da­tion window

Now, we have a drop-down list (Fig. 3)

A drop-down list
Fig. 3 A drop-down list

Since our cells with data are in a table, when we add a new line to the table, it also involves the drop-down list. 

Even, if we cut and paste our new data, the cells in the select­ed col­umn will still have the drop-down list. What’s more, in the newest Excel ver­sion, we have even Lookup options. We just have to start writ­ing the first let­ter of a word we’re look­ing for, then press the Tab key.

Lookup option
Fig. 4 Lookup option

This func­tion, how­ev­er, does­n’t work when we start from the mid­dle of our text. It works only with the first letter. 

https://www.youtube.com/watch?v=NMhYSgf0O3s