Verywellmind.com define intelligence as 

Despite substantial interest in the subject, there still isn't a consensus among experts about the components of intelligence or whether accurate measurements of intelligence are even possible.

Although contemporary definitions of intelligence vary considerably, experts generally agree that intelligence involves mental abilities such as logic, reasoning, problem-solving, and planning. Specifically, current definitions tend to suggest that intelligence is the ability to:

Learn from experience: The acquisition, retention, and use of knowledge is an important component of intelligence.
Recognize problems: To use knowledge, people first must identify the problems it might address.
Solve problems: People must then use what they have learned to come up with solutions to problems.1

Research on intelligence plays a significant role in many areas including educational program funding, job applicant screening, and testing to identify children who need additional academic help.