ما معنى Likelihood function, maximum likelihood estimator, score, Fisher information؟

For independent observations with density $f(x; \theta)$, the likelihood function is $\theta \mapsto \prod_if(X_i; \theta)$ and the log-likelihood $\ell_n(\theta) = \sum_i\ln f(X_i; \theta)$. The maximum likelihood estimator (MLE) maximises it. The score function is $\nabla_\theta\ln f(X; \theta)$, and the Fisher information is $\mathcal I(\theta) = \E[\nabla\ln f\,\nabla\ln f^\top] = -\E[\nabla^2\ln f]$ per observation.