Strike rate refers to two different statistics in the sport of cricket. Batting strike rate is a measure of how frequently a batsman achieves the primary goal of batting, namely scoring runs. Bowling strike rate is a measure of how frequently a bowler achieves the primary goal of bowling, namely taking wickets (i.e. getting batsmen out).
Both strike rates are relatively new statistics, having only been invented and considered of importance after the introduction of One Day International cricket in the 1970s.
Batting strike rate is defined for a batsman as the average number of runs scored per 100 balls faced. The higher the strike rate, the more effective a batsman is at scoring quickly.
In Test cricket, a batsman's strike rate is of secondary relevance to his ability to score runs without getting out. This means a Test batsman's most important statistic is generally considered to be his batting average, rather than his strike rate. However, given players of similar batting averages, the one with the higher strike rate would be considered a better batsman.
In limited overs cricket, strike rates are of considerably more importance. Since each team only faces a limited number of balls in an innings, the faster a batsman scores, the more runs his team will be able to accumulate. Oneday International batsmen should have a strike rate of 75.0 or more to be considered effective and strike rates of over 150 are becoming common in Twenty20 cricket.^{[1]} Strike rate or s/r as it is abbreviated to, is probably considered by most as the key factor in a batsman in one day cricket. Accordingly the batsmen with the higher strike rate, especially in Twenty20 matches, are more valued than those with a lesser strike rate.
Bowling strike rate is defined for a bowler as the average number of balls bowled per wicket taken. The lower the strike rate, the more effective a bowler is.
Although introduced as a statistic complementary to the batting strike rate during the ascension of oneday cricket in the 1980s, bowling strike rates are arguably of more importance in Test cricket than Oneday Internationals. This is because the primary goal of a bowler in Test cricket is almost always to take wickets, whereas in a oneday match it is often sufficient to bowl economically  giving away as few runs as possible even if this means taking fewer wickets.
A Test bowling strike rate below 60.0 is considered good, whereas in Oneday Internationals a strike rate needs to be below 40.0 to be considered good. The difference arises because in Test cricket the batsmen are much more concerned about preserving their wickets, and collecting runs over extended periods, whereas in Oneday Internationals batsmen are expected to take risks to score runs very quickly, and so it is considerably more difficult to get a batsman out in Test cricket compared to Oneday Internationals.

