xG (expected goals) is the sum of the probabilities of each shot being scored. Higher than actual goals means poor finishing; lower means few chances were taken well. The provider (API-Football) only supplies xG totals for the match and each half — the lines between 0′·HT·FT are not measured data.

Momentum — In-house calculation · An event at minute t is added over minutes t~t+5 with weight w×(1−k/6): goal 1.0 · own goal 0.5 · missed penalty 0.8 · opposition yellow card 0.25 · opposition red card 0.5. Value = home − away. Momentum control is recorded when |value| ≥ 0.15 in the same direction for at least 10 minutes. (Only goal and card events are used, as the provider does not supply minute-by-minute shots or corners)

Source: API-Football (scores, events, team stats, xG). Momentum is calculated by this site.