Spelling

The AutoCorrect feature helps you to fix common typing errors before they become actual spelling mistakes.
It is definitely always worth checking your text for any spelling mistakes and this can be done easily using the Spelling dialog box.
There are several ways you can display the Spelling dialog box and the easiest one is to use the button on the Standard toolbar.

Spelling - This can be found on the Standard toolbar.

Alternatively you can also select (Tools > Spelling) or you can use the shortcut key (F7).
Using the spell checker should not a be a substitute for reading through your presentation before you present it.
The spell checker will only check that the words appear in the dictionary. It will not check that they are in the correct order and that the sentence or bullet necessarily makes any sense.

What can you Check ?

Excel will only check the spelling on the active worksheet. If you want to check the spelling on the whole workbook you must select all the worksheets first.
If you select a single cell, the entire worksheet will be checked, including hidden cells, comments, chart and graphic objects and headers & footers.
Highlighting a range of cells before displaying the Spelling dialog box will mean only those cells are checked.
You can check the contents of an individual cell by double-clicking on the cell or by pressing F2 before selecting (Tools > Spelling).
If the formula bar is active then Excel checks just the contents of the formula bar.
It is possible to check individual words within a cell by highlighting the words in the formula bar before displaying the (Tools > Spelling) dialog box.

The Spelling dialog box

You can select (Tools > Spelling) when only one cell is selected to check the entire worksheet.
This searches all your slides, not just the active one.
The Spelling dialog box will open displaying the first word that cannot be found in the active dictionary.
Any cells that are hidden, including those in outlines will also be checked although any cells containing formulas will not be.
If the spell checker does not have any suggestions then you can type in your own correct and select "Change".
If the word you type is not in the directory then you are prompted to confirm.
If you get annoyed with this prompt you can click "Add" to permanently add it to your dictionary.

Not in Dictionary - This displays any words that cannot be found in the active dictionary. You can edit this word directly to replace it with a different word.
Suggestions - This displays a list of similar words or words which Excel thinks are likely replacements. You can replace the word with a suggestion by selecting one from the list and pressing the "Change" button.
Ignore Once - This ignores just this occurrence of the word displayed in the "Not in Dictionary" box. If the same word or text is found again on the worksheet then it will be identified as another mistake. The next time the Spelling is checked on this worksheet this word will still be identified as being unknown.
Ignore All - This ignores all the occurrences of the word displayed in the "Not in Dictionary" box. If the same word or text is found again on the worksheet then, it will be ignored. The next time the Spelling is checked on this worksheet this word (and all occurrences of it) will still be identified as unknown.
Add to Dictionary - This adds the word displayed in the "Not in Dictionary" box to the active custom dictionary. This will mean that the word is never flagged up again.
Change - This replaces just this occurrence of the word displayed in the "Not in Dictionary" box with the word that has been selected in the suggestions list.
Change All - This replaces all the occurrences of the word displayed in the "Not in Dictionary" box with the word that has been selected in the suggestions list.
AutoCorrect - This adds the word displayed in the "Not in Dictionary" box to the AutoCorrect list using the word that has been selected in the suggestions list as its automatic replacement.
Selecting Cancel closes the spelling dialog box and lets you quit the spelling check at any time.
The caption on the Cancel button will change to Close if you select Change, Change All or Add. The appearance of the Close button indicates that a change has been made either to the worksheet or to the active custom dictionary.
When the spell check has finished you will be prompted with a message asking you if you want to start checking again.

Removing Duplicate Words

In addition to spelling mistakes, the spell checker will also find other typographical errors such as repeated words an non standard capitalization (MicroSoft instead of Microsoft).
The caption on the Change button has changed to "Delete".

Delete - The duplicate words will be removed although the extra space will still be left ??

Create a custom Dictionary

It is also possible to create a custom dictionary that you may use to store any technical terms.

The spell checker actually uses two dictionaries. The standard dictionary and then the custom dictionary
The custom dictionary is shared by all the Office programs and can be found in the following place
SS - where ??
custom.dic
If you want to open this file it is best to use Word.
(Tools > Options)(Spelling and Style tab) custom dictionaries, select the custom.dic and select Modify.

When you add words to the dictionary, PowerPoint defaults by adding them to the "Custom.dic" which can be found in the following locations:
PowerPoint 365 - Proof/
PowerPoint 2021 -
PowerPoint 2019 -
PowerPoint 2016 -

Clear the contents of the "Add words to" box and type in the name of your new dictionary.
Alternative dictionaries include French and Spanish.
You cannot add any words to a new custom dictionary until you start to spell check a worksheet.
Select the Options button at the bottom of the spelling dialog box.
Click Add Word To" combo box and edit the name of the dictionary.
When editing the filename be sure not to delete the "custom.dic" name ?
Any words after this will be added to your new custom dictionary until you change it back.
When you spell check a worksheet every word is looked up in the built-in dictionary.

??

The spell checker can also check your punctuation and capitalisation to ensure it is consistent
These features are turned off my default
(Tools > Options)(Spelling and Style tab) Check style checkbox
SS

The office assistant is used to inform you of any inconsistencies
Style dialog SS
Case and end punctuation - ensure your capitalisation and punctuation are consistent
visual clarity - if you use too many fonts, titles etc

The defaults work pretty well, only change them if you need to

Important

Excel will only check the spelling on the active worksheet. If you want to check the spelling on the whole workbook you must select all the worksheets first.
You can spell check just a particular cell range by highlighting the cell range first before displaying the Spelling dialog box.
You can also edit the dictionary directly using Notepad.
You can also save print settings enabling you to save multiple print-setups for the same worksheet. For more details please refer to the Custom Views page.
You can select (Tools > Spelling) when the formula bar is active you can check just the contents of the active cell.