May you can explain this for a poor schoolboy like me 
If I do a curl to the node exporter I get mainly key/value pairs
# HELP go_memstats_alloc_bytes Number of bytes allocated and still in use.
# TYPE go_memstats_alloc_bytes gauge
go_memstats_alloc_bytes 1.562352e+06
# HELP go_memstats_alloc_bytes_total Total number of bytes allocated, even if freed.
# TYPE go_memstats_alloc_bytes_total counter
go_memstats_alloc_bytes_total 1.562352e+06
# HELP go_memstats_buck_hash_sys_bytes Number of bytes used by the profiling bucket hash table.
# TYPE go_memstats_buck_hash_sys_bytes gauge
go_memstats_buck_hash_sys_bytes 1.445247e+06
# HELP go_memstats_frees_total Total number of frees.
# TYPE go_memstats_frees_total counter
go_memstats_frees_total 570
For some we see also items in the key:
# TYPE node_cpu_scaling_frequency_max_hertz gauge
node_cpu_scaling_frequency_max_hertz{cpu="0"} 2.8e+09
node_cpu_scaling_frequency_max_hertz{cpu="1"} 2.8e+09
node_cpu_scaling_frequency_max_hertz{cpu="2"} 2.8e+09
node_cpu_scaling_frequency_max_hertz{cpu="3"} 2.8e+09
# HELP node_cpu_scaling_frequency_min_hertz Minimum scaled CPU thread frequency in hertz.
# TYPE node_cpu_scaling_frequency_min_hertz gauge
node_cpu_scaling_frequency_min_hertz{cpu="0"} 1.2e+09
node_cpu_scaling_frequency_min_hertz{cpu="1"} 1.2e+09
node_cpu_scaling_frequency_min_hertz{cpu="2"} 1.2e+09
node_cpu_scaling_frequency_min_hertz{cpu="3"} 1.2e+09
Looks to me as pretty good parsable but maybe I overlocked something