Why Likelihood Is Not a Probability?

From a Bayesian perspective, the reason the likelihood function isn't a probability density is that you haven't multiplied by a prior yet. But once you multiply by a prior distribution, the product is (proportional to) the posterior probability density for the parameters.

Is likelihood same as probability?

The distinction between probability and likelihood is fundamentally important: Probability attaches to possible results; likelihood attaches to hypotheses. ... There are only 11 possible results (0 to 10 correct predictions). The actual result will always be one and only one of the possible results.

Is a likelihood function a probability distribution?

Okay but the likelihood function is the joint probability density for the observed data given the parameter θ. As such it can be normalized to form a probability density function. So it is essentially like a pdf.