A strongly typed system is one that does not allow the conversion of data types during execution, in case there is a mismatch. For instance, if “18” is presented for an integer variable instead of 18, the system raises an error. Perl, Ruby, Python and Pascal are examples of strongly typed systems. 

In a Weakly typed system, the program allows flexibility to a certain degree for data type conversion. Such conversion may involve conversions from char to strings, integers to strings, decimals to integers or floats and so on. Shell, JavaScript, C, C++, and SQL are some examples of weakly typed systems.