तालाब या पोखर ऐसे जल-भरे गड्ढे को कहते हैं जो झील से छोटा हो, हालाँकि झील और तालाब के आकारों में अंतर बताने के लिये कोई औपचारिक मापदंड नहीं है। इनका मोटा-मोटा नाप लगभग २ हेक्टेयर से ८ हेक्टेयर तक का होता है। यूनाइटेड किंगडम में चैरिटी पॉण्ड कन्ज़र्वेशन नामक संस्था की परिभाषा के अनुसार 'तालाब एक कृत्रिम या प्राकृतिक जलाशय है जिसका सतही माप १ वर्ग मी. और २ हेक्टेयर के बीच हो और जिसमें वर्ष में कम से कम चार माह जल भरा रहे।

A pond is a small, still, land-based body of water formed by pooling inside a depression, either naturally or artificially. A pond is smaller than a lake and there are no official criteria distinguishing the two, although defining a pond to be less than 5 hectares in area, less than 5 metres (16 ft) in depth and with less than 30% with emergent vegetation helps in distinguishing the ecology of ponds from those of lakes and wetlands. Ponds can be created by a wide variety of natural processes, or they can simply be isolated depressions filled by runoff, groundwater, or precipitation, or all three of these. They can be further divided into four zones: vegetation zone, open water, bottom mud and surface film. The size and depth of ponds often varies greatly with the time of year; many ponds are produced by spring flooding from rivers. Ponds are usually freshwater but may be brackish in nature. Saltwater pools, with a direct connection to the sea to maintain full salinity, may sometimes be called 'ponds' but these are normally regarded as part of the marine environment. They do not support fresh or brackish water-based organisms, and are rather tidal pools or lagoons.