Use COUNTIF, one of the statistical functions, to count the number of cells that meet a criterion; for example, to count the number of times a particular city appears in a customer list.
Note: The COUNTIF function does not directly support data or ranges based upon the background color or font color of data cells. Excel supports the definition of UserDefined Functions (UDFs) using the Microsoft Visual Basic for Applications Editor, to support for Excel operations on cells and tables employing color for data marking. (Press Alt+F11 to open the Editor.)
Syntax
COUNTIF(range, criteria)
For example:

=COUNTIF(A2:A5,"apples")

=COUNTIF(A2:A5,A4)
Argument name 
Description 
range (required) 
The group of cells you want to count. Range can contain numbers, arrays, a named range, or references that contain numbers. Blank and text values are ignored. Learn how to select ranges in a worksheet. 
criteria (required) 
A number, expression, cell reference, or text string that determines which cells will be counted. For example, you can use a number like 32, a comparison like ">32", a cell like B4, or a word like "apples". COUNTIF uses only a single criteria. Use COUNTIFS if you want to use multiple criteria. 
Examples
To use these examples in Excel, copy the data in the table below, and paste it in cell A1 of a new worksheet.
Data 
Data 
apples 
32 
oranges 
54 
peaches 
75 
apples 
86 
Formula 
Description 
=COUNTIF(A2:A5,"apples") 
Counts the number of cells with apples in cells A2 through A5. The result is 2. 
=COUNTIF(A2:A5,A4) 
Counts the number of cells with peaches (using criterion in A4) in cells A2 through A5. The result is 1. 
=COUNTIF(A2:A5,A3)+COUNTIF(A2:A5,A2) 
Counts the number with oranges (using criterion in A3) and apples (using criterion in A2) in cells A2 through A5. The result is 3. This formula uses two COUNTIF expressions to specify multiple criteria, one criteria per expression. 
=COUNTIF(B2:B5,">55") 
Counts the number of cells with a value greater than 55 in cells B2 through B5. The result is 2. 
=COUNTIF(B2:B5,"<>"&B4) 
Counts the number of cells with a value not equal to 75 in cells B2 through B5. The ampersand (&) merges the comparison operator for not equal to (<>) and the value in B4 to read =COUNTIF(B2:B5,"<>75"). The result is 3. 
=COUNTIF(B2:B5,">=32")COUNTIF(B2:B5,">85") 
Counts the number of cells with a value greater than (>) or equal to (=) 32 and less than (<) or equal to (=) 85 in cells B2 through B5. The result is 3. 
=COUNTIF(A2:A5,"*") 
Counts the number of cells containing any text in cells A2 through A5. The asterisk (*) is used as the wildcard character to match any character. The result is 4. 
=COUNTIF(A2:A5,"?????es") 
Counts the number of cells that have exactly 7 characters that end with the letters "es" in cells A2 through A5. The question mark (?) is used as the wildcard character to match individual characters. The result is 2. 
=COUNTIF(fruit,">=32")COUNTIF(fruit,">85") 
Uses a named range (applied to cells A2:A5) to count the number of cells with a value greater than 55 in cells B2 through B5. The result is 2. 
Common Problems
Problem 
What went wrong 
Wrong value returned for long strings. 
The COUNTIF function returns incorrect results when you use it to match strings longer than 255 characters. To match strings longer than 255 characters, use the CONCATENATE function or the concatenate operator &. For example, =COUNTIF(A2:A5,"long string"&"another long string"). 
No value returned when you expect a value. 
Be sure to enclose the criteria argument in quotes. 
A COUNTIF formula receives a #VALUE! error when referring to another worksheet. 
This error occurs when the formula that contains the function refers to cells or a range in a closed workbook and the cells are calculated. For this feature to work, the other workbook must be open. 
Best practices
Do this 
Why 
Be aware that COUNTIF ignores upper and lower case in text strings. 
Criteria aren't case sensitive. In other words, the string "apples" and the string "APPLES" will match the same cells. 
Use wildcard characters. 
Wildcard characters —the question mark (?) and asterisk (*)—can be used in criteria. A question mark matches any single character. An asterisk matches any sequence of characters. If you want to find an actual question mark or asterisk, type a tilde (~) in front of the character. For example, =COUNTIF(A2:A5,"apple?") will count all instances of "apple" with a last letter that could vary. 
Make sure your data doesn't contain erroneous characters. 
When counting text values, make sure the data doesn't contain leading spaces, trailing spaces, inconsistent use of straight and curly quotation marks, or nonprinting characters. In these cases, COUNTIF might return an unexpected value. You may need to remove trailing spaces in a cell after table values to get accurate results. Try using the CLEAN function or the TRIM function. 
For convenience, use named ranges 
COUNTIF supports named ranges in a formula (such as =COUNTIF(fruit,">=32")COUNTIF(fruit,">85"). The named range can be in the current worksheet, another worksheet in the same workbook, or from a different workbook. To reference from another workbook, that second workbook also must be open. 
Related

To count cells that aren't blank, use the COUNTA function.

To count cells using multiple criteria, use the COUNTIFS function.

Use the CLEAN function or the TRIM function to remove leading spaces in table values.

Learn more about errors in worksheets, like #N/A, #REF, and #Name?.

See a video on how to use the COUNTIFS function.